Rename content files to their desired name

[fsimonis]

We need to rename files of pages to their desired name by removing their prefix.
This shouldn't matter in Jekyll as we already use permalinks for every page.

Examples:

• content/docs/configuration/advanced/configuration-action.md becomes content/docs/configuration/advanced/-action.md
• content/docs/installation/building-from-source/installation-source-configuration.md becomes content/docs/installation/building-from-source/configuration.md

[kss682]

I assume files like tutorials.md in content/tutorials/ would be mapped to _index.md (Similarly for other sections) ?

[fsimonis]

It's often helpful to check the permalinks as well as the menu of the live website to figure out what the intent of a file is.

tutorials.md for example is a bit weird as it is published as /tutorials.html, but shows up in the side menu as overview.

To get us started, let's rename it to tutorials/overview.md for now.