Docs: add custom descriptions to most relevant docs

doc/README.md

 ---
 comments: false
+description: 'Learn how to use and administer GitLab, the most scalable Git-based fully integrated platform for software development.'
 ---
 # GitLab Documentation

doc/administration/index.md

+---
+description: 'Learn how to install, configure, update, and maintain your GitLab instance.'
+---
+
 # Administrator documentation **[CORE ONLY]**
 Learn how to administer your GitLab instance (Community Edition and

doc/administration/pages/index.md

+---
+description: 'Learn how to administer GitLab Pages.'
+---
+
 # GitLab Pages administration
 > **Notes:**
@@ -8,8 +12,6 @@
   GitLab from source, follow the [Pages source installation document](source.md).
 - To learn how to use GitLab Pages, read the [user documentation][pages-userguide].
----
-
 This document describes how to set up the _latest_ GitLab Pages feature. Make
 sure to read the [changelog](#changelog) if you are upgrading to a new GitLab
 version as it may include new features and changes needed to be made in your
@@ -24,8 +26,6 @@ SNI and exposes pages using HTTP2 by default.
 You are encouraged to read its [README][pages-readme] to fully understand how
 it works.
----
-
 In the case of [custom domains](#custom-domains) (but not
 [wildcard domains](#wildcard-domains)), the Pages daemon needs to listen on
 ports `80` and/or `443`. For that reason, there is some flexibility in the way

doc/ci/README.md

 ---
 comments: false
+description: "Learn how to use GitLab CI/CD, the GitLab built-in Continuous Integration, Continuous Deployment, and Continuous Delivery toolset to build, test, and deploy your application."
 ---
 # GitLab Continuous Integration (GitLab CI/CD)

doc/development/README.md

 ---
 comments: false
+description: 'Learn how to contribute to GitLab.'
 ---
 # GitLab development guides

doc/development/doc_styleguide.md

+---
+description: 'Writing styles, markup, formatting, and reusing regular expressions throughout the GitLab Documentation.'
+---
+
 # Documentation style guidelines
 The documentation style guide defines the markup structure used in

doc/development/writing_documentation.md

+---
+description: Learn how to contribute to GitLab Documentation.
+---
+
 # GitLab Documentation guidelines
   - **General Documentation**: written by the [developers responsible by creating features](#contributing-to-docs). Should be submitted in the same merge request containing code. Feature proposals (by GitLab contributors) should also be accompanied by its respective documentation. They can be later improved by PMs and Technical Writers.

doc/install/README.md

 ---
 comments: false
+description: Read through the GitLab installation methods.
 ---
 # Installation

doc/install/azure/index.md

+---
+description: 'Learn how to spin up a 
+pre-configured GitLab VM on Microsoft Azure and have your very own private GitLab instance up and running in around 30 minutes.'
+---
+
 # Install GitLab on Microsoft Azure
 > _This article was originally written by Dave Wentzel and [published on the GitLab Blog][Original-Blog-Post]._

doc/install/google_cloud_platform/index.md

+---
+description: 'Learn how to install a GitLab instance on Google Cloud Platform.'
+---
+
 # Installing GitLab on Google Cloud Platform
 ![GCP landing page](img/gcp_landing.png)

doc/install/kubernetes/index.md

+---
+description: 'Read through the different methods to deploy GitLab on Kubernetes.'
+---
+
 # Installing GitLab on Kubernetes
+
 > **Note**: These charts have been tested on Google Kubernetes Engine and Azure Container Service. Other Kubernetes installations may work as well, if not please [open an issue](https://gitlab.com/charts/charts.gitlab.io/issues).
 The easiest method to deploy GitLab on [Kubernetes](https://kubernetes.io/) is
@@ -16,6 +21,7 @@ should be deployed, upgraded, and configured.
   * [Community Contributed Charts](#community-contributed-charts): Community contributed charts, deprecated by the official GitLab chart.
 ## GitLab-Omnibus Chart (Recommended)
+
 > **Note**: This chart is in beta while [additional features](https://gitlab.com/charts/charts.gitlab.io/issues/68) are being added.
 This chart is the best available way to operate GitLab on Kubernetes. It deploys and configures nearly all features of GitLab, including: a [Runner](https://docs.gitlab.com/runner/), [Container Registry](../../user/project/container_registry.html#gitlab-container-registry), [Mattermost](https://docs.gitlab.com/omnibus/gitlab-mattermost/), [automatic SSL](https://github.com/kubernetes/charts/tree/master/stable/kube-lego), and a [load balancer](https://github.com/kubernetes/ingress/tree/master/controllers/nginx). It is based on our [GitLab Omnibus Docker Images](https://docs.gitlab.com/omnibus/docker/README.html).

doc/topics/git/how_to_install_git/index.md

@@ -4,6 +4,7 @@ author_gitlab: SeanPackham
 level: beginner
 article_type: user guide
 date: 2017-05-15
+description: 'This article describes how to install Git on macOS, Ubuntu Linux and Windows.'
 ---
 # Installing Git

doc/user/index.md

+---
+description: 'Read through the GitLab User documentation to learn how to use, configure, and customize GitLab and GitLab.com to your own needs.'
+---
+
 # User documentation
 Welcome to GitLab! We're glad to have you here!

doc/user/permissions.md

+---
+description: 'Understand and explore the user permission levels in GitLab, and what features each of them grants you access to.'
+---
+
 # Permissions
 Users have different abilities depending on the access level they have in a

doc/user/project/pages/index.md

+---
+description: 'Learn how to use GitLab Pages to deploy a static website at no additional cost.'
+---
+
 # GitLab Pages
 With GitLab Pages it's easy to publish your project website. GitLab Pages is a hosting service for static websites, at no additional cost.