Add footer extra links template (#9576)

* Add footer extra links template

* [Docs] Update to mention extra links footer template

* Commit suggestion from @davidsvantesson

Co-Authored-By: David Svantesson <davidsvantesson@gmail.com>

* Move template placement to right side of footer

Co-authored-by: David Svantesson <davidsvantesson@gmail.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

docs/content/doc/advanced/customizing-gitea.en-us.md

@@ -80,10 +80,10 @@ Dont forget to restart your gitea to apply the changes.
 
 ### Adding links and tabs
 
-If all you want is to add extra links to the top navigation bar, or extra tabs to the repository view, you can put them in `extra_links.tmpl` and `extra_tabs.tmpl` inside your `custom/templates/custom/` directory.
+If all you want is to add extra links to the top navigation bar or footer, or extra tabs to the repository view, you can put them in `extra_links.tmpl` (links added to the navbar), `extra_links_footer.tmpl` (links added to the left side of footer), and `extra_tabs.tmpl` inside your `custom/templates/custom/` directory.
 
 For instance, let's say you are in Germany and must add the famously legally-required "Impressum"/about page, listing who is responsible for the site's content:
-just place it under your "custom/public/" directory (for instance `custom/public/impressum.html`) and put a link to it in `custom/templates/custom/extra_links.tmpl`.
+just place it under your "custom/public/" directory (for instance `custom/public/impressum.html`) and put a link to it in either `custom/templates/custom/extra_links.tmpl` or `custom/templates/custom/extra_links_footer.tmpl`.
 
 To match the current style, the link should have the class name "item", and you can use `{{AppSubUrl}}` to get the base URL:
 `<a class="item" href="{{AppSubUrl}}/impressum.html">Impressum</a>`

templates/base/footer_content.tmpl

@@ -19,6 +19,7 @@
 			<a href="{{StaticUrlPrefix}}/vendor/librejs.html" data-jslicense="1">JavaScript licenses</a>
 			{{if .EnableSwagger}}<a href="{{AppSubUrl}}/api/swagger">API</a>{{end}}
 			<a target="_blank" rel="noopener noreferrer" href="https://gitea.io">{{.i18n.Tr "website"}}</a>
+			{{template "custom/extra_links_footer" .}}
 			{{if (or .ShowFooterVersion .PageIsAdmin)}}<span class="version">{{GoVer}}</span>{{end}}
 		</div>
 	</div>