Update issue templates

Define new issue templates following new structure for them.

Also add a new template related to site config.

.github/ISSUE_TEMPLATE/fetching-content.md

@@ -0,0 +1,24 @@
+---
+name: Fetching content
+about: If wallabag can't extract content for an URL
+title: Wrong display in wallabag (HOST)
+labels: Site Config
+assignees: ''
+
+---
+
+**Before submitting the issue, please read:**
+If wallabag can't parse / extract content for a given link, please first read the documentation about it:
+http://doc.wallabag.org/en/user/errors_during_fetching.html#how-can-i-help-to-fix-that
+
+We have a lot of request about fetching config issue. It'll help us a lot if you give a try to fix it on your own following the doc.
+If you failed to fix it yourself, tick the following box:
+- [ ] I've tried myself without success
+- [ ] I've replaced `HOST` in the issue title with the host of the URL that can't be fetched (ie: `nytimes.com`, `20minutes.fr`, `bbc.com`, etc.)
+
+**Content related:**
+ - URL: [full url of the content]
+ - wallabag version: [e.g. 2.4.0]
+
+**Describe what's wrong:**
+A clear and concise description of what you expected to happen.