General purpose reformating and rewording in (a few places). This should
also make markdown linting happier.
Prefer back-ticks wherever useful and use `console` for code blocks to
be executed on terminal.
Also, update references links wherever possible (including update from
'http://' to 'https://').
There are a number of things happening here.
- Extra support for yaourt has been removed
- Docs have been updated to explicitly call out that AUR helpers are not
officially supported
- aurutils has been suggested to make common operations easier
- A utility function called aurget (similar to aurfetch from aurutils)
has been added to make cloning AUR repos easier.
Fixes#1531
