Prepare update guide for 8.8

See merge request !391

Reduce emails-on-push HTML size by using a simple monospace font

With this simple change we reduce the size dramatically by reducing every inlined CSS instance of this:

font-family: 'Menlo', 'Liberation Mono', 'Consolas', 'DejaVu Sans Mono', 'Ubuntu Mono', 'Courier New', 'andale mono', 'lucida console', monospace"

to this:

font-family: monospace

Before:

![image](/uploads/6ce445102dfe5bfcdf9cf3479218b0ad/image.png)

After:

![image](/uploads/8e3a4216815986543ece75483d7f9063/image.png)

Helps gitlab-org/gitlab-ce#15178

See merge request !384

Updated EE CHANGELOG per 8-7-stable-ee

See merge request !390

[ci skip]

Fix LDAP access level spillover bug

See merge request !499

ES: Refactoring

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/516

See merge request !365

Mask credentials in URLs instead of remove them

REF: #447 

REF: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/382#note_11713978

See merge request !385

Also refactored Project#safe_import_url

With this simple change we reduce the size dramatically by reducing every instance of this:

font-family: 'Menlo', 'Liberation Mono', 'Consolas', 'DejaVu Sans Mono', 'Ubuntu Mono', 'Courier New', 'andale mono', 'lucida console', monospace"

to this:

font-family: monospace

Helps #15178

Don't expose URL credentials in errors generated by Mirror sync.

REF: #447 

See merge request !382

Fix typo



See merge request !379

* I introduced the new UrlSanitizer class which can help us to protect
credentials used in URLs.
* Renames `.process` class method to `.sanitize`

With this fix we remove the credentials from the repo URLs that are shown when
there is an internal error with Git

ES: Add more rake tasks



See merge request !381

Update elasticsearch.md with more details

Added info for running the index for all available indexes and clarification about how the process keep ElasticSearch up-to-date

See merge request !369

Add sort by weight in issuable filter

Fixes #537 

See merge request !378

ES: More efficient snippets search

https://gitlab.com/gitlab-org/gitlab-ee/issues/375

See merge request !371

CE upstream



See merge request !377

Delete ProjectImportData record only if Project is not a mirror.

This fix ensure we always use the full import URL when syncing the
mirror.

REF: https://gitlab.com/gitlab-org/gitlab-ce/issues/17065

See merge request !370

Use 'exec' in Unicorn and Sidekiq launch scripts

When running Unicorn or Sidekiq in the foreground this change removes
an intermediate /bin/sh process. This makes process supervision in the
GitLab Development Kit more reliable.

This change does not affect Omnibus-GitLab (because there we do not
use these launch scripts). Installations from source do use the launch
scripts but for the standard GitLab init script this change will not
make a difference.

Custom installations using Upstart or Systemd may be affected however,
because under certain configurations these systems count exactly how
many forks happen during process startup, and we are reducing that
number by one here.

Closes https://gitlab.com/gitlab-org/gitlab-development-kit/issues/116

See merge request !3964

Use Rugged's TagCollection#create instead of gitlab-shell's Repository#add_tag for better performance

This was originally opened at !1757 by @pcarranza but I changed it to use Rugged instead of gitlab_git, following @DouweM's request.

Once this is merged, https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/26 will be mergeable too.

See merge request !3745

Fix typo in user steps feature file

Just came across a typo in the user steps file.

See merge request !3943

Update patch_versions.md with explicit --with statement for db gem group

## What does this MR do?
Updates `patch_versions.md`'s instructions on installing gems to explicitly install either the postgres or mysql groups.

## Are there points in the code the reviewer needs to double check?
No, but thank you for your time.

## Why was this MR needed?
I performed the steps listed in `patch_versions.md` and ran the command for updating postgres gems. Bundler told me at the end that it had not installed the postgres gem group, which caused the next step, migrating the DB, to fail for obvious reasons.

Changing the command to `--with postgres` made it install the postgres gem group, and db:migrate then passed.

## What are the relevant issue numbers?
None

## Screenshots (if relevant)
N/A

See merge request !3955

# Conflicts:
#	Gemfile.lock