…6494)

Honour the git-authors plugin's setting to render the authors' names
as links pointing to their email address:

* If the git-authors plugin is enabled and its show_email_address
  option is not set, or is set to true, render the author's name as a
  "mailto:" link.
* If the git-authors plugin is enabled and its show_email_address
  option is set to false, render the author's name in plain text with
  no link.
* If the git-authors plugin is not enabled (or not installed), don't
  show author information.

* added code and tooltips to custom site feedback

- clarifying that the feedback widget needs to be turned on
- showing how to disable the form and
- show the notes that are configured

* undoing a minor change that we unnecessary

- I changed a colon to a full stop at some point because I thought I
  would add another sentence, decided not to and then the unneeded
  change ended up in the previous commit.

* turned a comment I deleted into a tooltip

Co-authored-by: LordDeatHunter <26803198+LordDeatHunter@users.noreply.github.com>

* Removed unused imports

* Replaced nested `if` statements by single one

* Removed unnecessary `dict()` constructor around `dict` literal

This is in response to
#6542
to add a section on setting up navigation for a blog so that the archive
and category pages appear in the right place.