Update memory requirements docs

## What does this MR do?
It doubles the memory requirements in the docs.

## Are there points in the code the reviewer needs to double check?
N/A

## Why was this MR needed?
To reflect the requirements for decent operation, until we bring such requirements down.

## What are the relevant issue numbers?
https://gitlab.com/gitlab-com/infrastructure/issues/19

## Screenshots (if relevant)
N/A

## Does this MR meet the acceptance criteria?

- [] ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] ~~API support added~~
- ~~Tests~~
  - [ ] ~~Added for this feature/bug~~
  - [ ] ~~All builds are passing~~
- [ ] ~~Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)~~
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !6016

Change the inline code to codeblocks for the new features doc guideline

Change the inline code to codeblocks for the new features doc guideline
for better clarity.

See merge request !6168

[ci skip]

Update CHANGELOG with 8.11.4 entries.



See merge request !6159

Remove inconsistent font weight for sidebar's labels

## What does this MR do?
Removes the `.bold` css class from the sidebar label default value so that it is no longer bold :smile: 

**None** => None

## Are there points in the code the reviewer needs to double check?
None

## Why was this MR needed?
Fixes a UI inconsistency

## What are the relevant issue numbers?
Closes #21141 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-24_at_9.41.11_AM](/uploads/3e416d45531b7322474922c569225c03/Screen_Shot_2016-08-24_at_9.41.11_AM.png)

After:
![Screen_Shot_2016-08-24_at_9.40.57_AM](/uploads/a4d60d4cd0a57142ad6c0c8a25be5342/Screen_Shot_2016-08-24_at_9.40.57_AM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5984

Fix inconsistent checkbox alignment

## What does this MR do?
Vertically aligns the checkboxes to the top so that it is aligned with the issue titles

## Are there points in the code the reviewer needs to double check?
None

## Why was this MR needed?
Fixes existing UI inconsistency

## What are the relevant issue numbers?
Closes #21398

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-25_at_12.43.21_PM](/uploads/c494d6200e2068feb324db932851cdc0/Screen_Shot_2016-08-25_at_12.43.21_PM.png)

After:
![Screen_Shot_2016-08-25_at_12.41.51_PM](/uploads/42241a150c886592ff92a5840090c589/Screen_Shot_2016-08-25_at_12.41.51_PM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !6032