pidgin/nest

Unify contents of contributing section into a single page

2021-07-04, Sorvival
74890bc9a66d
Unify contents of contributing section into a single page

- Add some basic content to the index of the development section so that
it's not empty
- Remove contributing/mercurial page since its contents are now in the docs
page for using mercurial or in the (now single) contributing page.
- Add section in contributing page that points to useful link on how to
contribute code.
- Minor cleanups in the pre-existing contributing page
- Fix broken link in about index page that appeared after moving the
contributing section into a single page.

Testing Done:
Ran dev-server.sh and verified contents of the website looked as intended

Bugs closed: NEST-33

Reviewed at https://reviews.imfreedom.org/r/789/
{{ range sort .Site.Data.gsoc "year" "desc" }}
<h3 id="gsoc-{{ .year }}">{{ .year }}</h3>
<table>
<thead>
<th>{{ T "Project" }}</th>
<th>{{ T "Student" }}</th>
<th>{{ T "Mentor" }}</th>
<th>{{ T "Status" }}</th>
</thead>
<tbody>
{{ range .participants }}
<tr>
<td>{{ .project }}</td>
<td>{{ .student }}</td>
<td>{{ .mentor }}</td>
<td>{{ .status | markdownify }}</td>
</tr>
{{ end }}
</tbody>
</table>
{{ end }}