Replace uses of shorthand codeblock syntax to avoid issues with localization

Previously, many paragraphs in the documentation used `::` at the end of a line
as a replacement for a single colon (and `::` on the following line).
Due to this, the `::` was part of the extracted string for localization.
Weblate also showed a warning about the trailing `::`, as it's not
normally expected to be there.

This change requires translators to revalidate all modified strings.
However, considering many of those have broken code blocks due to translators
replacing `::` with `:`, it can be a good idea.

This also adds documentation writing guidelines for code blocks and admonitions.
This commit does not modify existing admonitions in any way (as this would
lead to a much larger diff, and require more localizable text to be revalidated
by translators).

tutorials/best_practices/project_organization.rst

@@ -113,7 +113,9 @@ in general).
 
 On Windows 10, to further avoid mistakes related to case sensitivity,
 you can also make the project folder case-sensitive. After enabling the Windows
-Subsystem for Linux feature, run the following command in a PowerShell window::
+Subsystem for Linux feature, run the following command in a PowerShell window:
+
+::
 
     # To enable case-sensitivity:
     fsutil file setcasesensitiveinfo <path to project folder> enable
@@ -123,6 +125,8 @@ Subsystem for Linux feature, run the following command in a PowerShell window::
 
 If you haven't enabled the Windows Subsystem for Linux, you can enter the
 following line in a PowerShell window *running as Administrator* then reboot
-when asked::
+when asked:
+
+::
 
     Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux