Configurable submit issues links

[ouuan]

By "submit issues links", I mean these lines:

docsy/layouts/partials/page-meta-links.html

Lines 17 to 22 in f19b852

	{{ $issuesURL := printf "%s/issues/new?title=%s" $gh_repo (htmlEscape $.Title )}}
	<a href="{{ $editURL }}" target="_blank"><i class="fa fa-edit fa-fw"></i> {{ T "post_edit_this" }}</a>
	<a href="{{ $issuesURL }}" target="_blank"><i class="fab fa-github fa-fw"></i> {{ T "post_create_issue" }}</a>
	{{ if $gh_project_repo }}
	{{ $project_issueURL := printf "%s/issues/new" $gh_project_repo }}
	<a href="{{ $project_issueURL }}" target="_blank"><i class="fas fa-tasks fa-fw"></i> {{ T "post_create_project_issue" }}</a>

Now the submit issues links are repo/issues/new, but one may want to use other links.

For example, a repo may have issue templates, but repo/issues/new won't let users choose the template, so one may want to use repo/issues/new/choose instead.

However, we can't simply use repo/issues/new/choose instead, otherwise ?title=%s will be broken, as the user will be redirected to repo/issues/new without parameters like ?title=%s if there's no issue template in the repo.

So, I suggest making these links customizable, or at least make it able to use repo/issues/new/choose instead of repo/issues/new.

An example of a repo with issue templates: https://github.com/cpeditor/cpeditor/issues/new/choose.