Revise main README for cleanup and some minor clarifications

* Fix typos, add links, add minor text changes
* Rephrase three section for clarity

[ci skip]

README.md

@@ -9,19 +9,19 @@
 - Each project can also have an issue tracker and a wiki
 - Used by more than 100,000 organizations, GitLab is the most popular solution to manage Git repositories on-premises
 - Completely free and open source (MIT Expat license)
-- Powered by Ruby on Rails
+- Powered by [Ruby on Rails](https://github.com/rails/rails)
 ## Editions
 There are two editions of GitLab.
-GitLab [Community Edition](https://about.gitlab.com/features/) (CE) is available without any costs under an MIT license.
-GitLab Enterprise Edition (EE) includes [extra features](https://about.gitlab.com/features/#compare) that are most useful for organizations with more than 100 users.
+*GitLab [Community Edition](https://about.gitlab.com/features/) (CE)* is available without any costs under an MIT license.
+*GitLab Enterprise Edition (EE)* includes [extra features](https://about.gitlab.com/features/#compare) that are most useful for organizations with more than 100 users.
 To get access to the EE and support please [become a subscriber](https://about.gitlab.com/pricing/).
 ## Canonical source
-- The source of GitLab Community Edition is [hosted on GitLab.com](https://gitlab.com/gitlab-org/gitlab-ce/) and there are mirrors to make [contributing](CONTRIBUTING.md) as easy as possible.
+The source of GitLab Community Edition is [hosted on GitLab.com](https://gitlab.com/gitlab-org/gitlab-ce/) and there are mirrors to make [contributing](CONTRIBUTING.md) as easy as possible.
 ## Code status
@@ -48,42 +48,45 @@ On [about.gitlab.com](https://about.gitlab.com/) you can find more information a
 ## Requirements
-- Ubuntu/Debian/CentOS/RHEL**
+GitLab requires the following software:
+
+- Ubuntu/Debian/CentOS/RHEL
 - Ruby (MRI) 2.0 or 2.1
-- git 1.7.10+
-- redis 2.0+
+- Git 1.7.10+
+- Redis 2.0+
 - MySQL or PostgreSQL
-** More details are in the [requirements doc](doc/install/requirements.md).
+Please see the [requirements documentation](doc/install/requirements.md) for system requirements and more information about the supported operating systems.
 ## Installation
-Please see [the installation page on the GitLab website](https://about.gitlab.com/installation/) for the various options.
-Since a manual installation is a lot of work and error prone we strongly recommend the fast and reliable [Omnibus package installation](https://about.gitlab.com/downloads/) (deb/rpm).
-You can access new installation with the login `root` and password `5iveL!fe`, after login you are required to set a unique password.
+The recommended way to install GitLab is using the provided [Omnibus packages](https://about.gitlab.com/downloads/). Compared to a manual installation, this is faster and less error prone. Just select your operating system, download the respective package (Debian or RPM) and install it using the system's package manager.
+
+There are various other options to install GitLab, please refer to the [installation page on the GitLab website](https://about.gitlab.com/installation/) for more information.
+
+You can access a new installation with the login **`root`** and password **`5iveL!fe`**, after login you are required to set a unique password.
 ## Third-party applications
-There are a lot of applications and API wrappers for GitLab.
-Find them [on our website](https://about.gitlab.com/applications/).
-## New versions
-Since 2011 a minor or major version of GitLab is released on the 22nd of every month. Patch and security releases come out when needed.  New features are detailed on the [blog](https://about.gitlab.com/blog/) and in the [changelog](CHANGELOG). For more information about the release process see the release [documentation](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/release). Features that will likely be in the next releases can be found on the [feature request forum](http://feedback.gitlab.com/forums/176466-general) with the status [started](http://feedback.gitlab.com/forums/176466-general/status/796456) and [completed](http://feedback.gitlab.com/forums/176466-general/status/796457).
+There are a lot of [third-party applications integrating with GitLab](https://about.gitlab.com/applications/). These include GUI Git clients, mobile applications and API wrappers for various languages.
+## GitLab release cycle
+Since 2011 a minor or major version of GitLab is released on the 22nd of every month. Patch and security releases are published when needed. New features are detailed on the [blog](https://about.gitlab.com/blog/) and in the [changelog](CHANGELOG). For more information about the release process see the [release documentation](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/release). Features that will likely be in the next releases can be found on the [feature request forum](http://feedback.gitlab.com/forums/176466-general) with the status [started](http://feedback.gitlab.com/forums/176466-general/status/796456) and [completed](http://feedback.gitlab.com/forums/176466-general/status/796457).
 ## Upgrading
-For updating the the Omnibus installation please see the [update documentation](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/update.md). For manual installations there is an [upgrader script](doc/update/upgrader.md) and there are [upgrade guides](doc/update).
+For updating the Omnibus installation please see the [update documentation](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/update.md). For manual installations there is an [upgrader script](doc/update/upgrader.md) and there are [upgrade guides](doc/update) detailing all necessary commands to migrate to the next version.
 ## Install a development environment
-We recommend setting up your development environment with [the GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit).
-If you do not use the GitLab Development Development kit you need to install and setup all the dependencies yourself, this is a lot of work and error prone.
+To work on GitLab itself, we recommend setting up your development environment with [the GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit).
+If you do not use the GitLab Development Kit you need to install and setup all the dependencies yourself, this is a lot of work and error prone.
 One small thing you also have to do when installing it yourself is to copy the example development unicorn configuration file:
     cp config/unicorn.rb.example.development config/unicorn.rb
-Instructions on how to start Gitlab and how to run the tests can be found in the [development section of the GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit#development).
+Instructions on how to start GitLab and how to run the tests can be found in the [development section of the GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit#development).
 ## Documentation