Add upgrade guide for 8.2 to 8.3

Making sure we don't forget mentioning the need to upgrade Redis from !1888 (merged). Added this in preparation for 8.3.

@stanhu

Added 1 commit:

• f2aab7eb - Rename gitlab-git-http-server mention with gitlab-workhorse

Added 1 commit:

• 9d86d598 - Rename gitlab-git-http-server mention with gitlab-workhorse

@stanhu The 8.2 to 8.3 guide shouldn't need the section on migrating from g-g-h-s to gitlab-workhorse, just a note about updating the version.

Added 65 commits:

• 9d86d598...45265157 - 62 commits from branch master
• 58bb985f - Add upgrade guide for 8.2 to 8.3
• 5bca9ec7 - Rename gitlab-git-http-server mention with gitlab-workhorse
• 264f4007 - Update gitlab-workhorse and remove mention of gitlab-git-http-server

Added 1 commit:

• b9b35012 - Update gitlab-workhorse and remove mention of gitlab-git-http-server

@rspeicher Got it. I've updated the document to update gitlab-workhorse to 0.4.3 with the assumption that's the version that will be released for 8.3.

Title changed from WIP: Add upgrade guide for 8.2 to 8.3 to Add upgrade guide for 8.2 to 8.3

mentioned in commit 63f58c49

Status changed to merged

Going to bump it back to 0.4.2. As far as I know there's not a 0.4.3 version pending.

mentioned in commit f67c6551

mentioned in commit 3aeae2c7

mentioned in commit d80dc2cb