Fix outline.

The pages are now html5.
The pages use nav, section, article for a better layout.
The pages have a better outline.
Add better introduction and Clever's side API doc.
publish stays in branch
better outline
Be clearer about authentication, and whos API which one is.
Add add-ons log collector API doc. Solves issues #3
Add hyphens to ensure consistency in naming.
Add link to log collector doc
Fix eu and be more precise on slug
Troubleshooting: clean up a bit.

ACK.
improve troubleshooting for git

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
War: document pingPaths
Merge branch 'master' of git+ssh://gitlab.clever-cloud.com/clever-cloud/doc.clever-cloud.com
Add environment injection documentation.
Be simpler in nodejs doc.
Fix sbt link
WAR: Add context support doc
table for var env + h4 styling for warnings
Fix position
Fix links and titles