Since 13.4, Debian 8 (jessie) support has already been dropped:
https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/4430



Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

This adds a document to describe the background for managing PG
extensions.

We have deprecated Internet Explorer 11 in 13.0 already. This removes
the extra case for it in the interface and the docs have been updated to
just indicate that we dropped it in 13.0.

The link to the feedback issue has been removed and users will still see
the outdated browser warning in case they use Internet Explorer

As discussed in
https://gitlab.com/gitlab-org/gitlab/-/issues/238216#note_398065789

In order to be able to make use of the reference-transaction hook in
Gitaly, the minimum required Git version was bumped to v2.28.0. But due
to a bug in the hook's implementation in git-core it cannot yet be used
reliably, and thus the new requirement doesn't make a lot of sense yet.
So let's remove the requirement and instead make v2.28.0 the recommended
version.

Note that previous requirements were inconsistent. Some parts noted that
Git v2.24.0 is required starting with GitLab 13.1, while other parts
said Git v2.25.0 is required. To avoid a retroactive bump, this commit
adjusts documentation to v2.24.0.

Gitaly is moving its minimum required version of Git to v2.28.0. Adjust
our documentation to match.

Move and merge the two documents about NFS into a new location

Add documentation on how to enable `btree_gist`, required from 13.1 and
onwards

Alert boxes should have a newline after the
initial alert text itself. Find and replace
to fix these.

Based on performance testing by Quality for Reference Architectures

Correct many external links to their new homes.

Rubinius' homepage is rather bare-bone as of
https://github.com/rubinius/rubinius.com/blame/b1b605a7f9834bc85e638064530bb057a7e74520/source/index.html

Corrected few spelling errors and grammatical errors in the file.

Update requirements.md
Corrected some of the grammatical and spelling errors in the file.

Update index.md

Update requirements.md

Update markdown.md

Apply suggestion to doc/install/requirements.md

Apply suggestion to doc/user/markdown.md

Apply suggestion to doc/user/snippets.md

Apply suggestion to doc/user/snippets.md

Links to issues need to be update to use a hyphen,
this MR changes issue links in dirs not covered
in other MRs.

Corrected few spelling errors and grammatical errors in the file.

- `availability/index.md` to `reference_architectures/index.md`
- `high_availability/index.md` to `reference_architectures/index.md`
- `scaling/index.md` to `reference_architectures/index.md`

Update links that were redirected or throw
404 errors

Specifying languages for more code blocks.

- Describe number of workers
- Describe number of threads

Also fix violations of the rule.

This adds a deprecation message for Internet Explorer 11. We are also
reformatting the outdated_browser alert style to match our new Pajamas
style of a `danger` alert.

We are also updating the documentation regarding this change.