docs: add contributing to sidebar
Added Contributing Guidelines to the introduction menu point on the sidebar.
I think it should be as obvious as possible.
Another good solution would be to add them to the top bar?
If this is merged, I will do the same changes for Kratos/Oathkeeper/Keto.
{
- "Introduction": ["index", "5min-tutorial", "install"],
+ "Introduction": ["index", "5min-tutorial", "install", "contributing"],
"Concepts": [
"concepts/before-oauth2",
"concepts/oauth2",
