Fixing some /Storage issues

[Deashow]

• merged "/linux/hidden-os-specific-partitioning.rst" to "/linux/hidden.rst"

• same for /mac and /windows

• deleting "hidden-os-specific-partitioning.rst" in /linux, /mac, /windows after merge

• testet seperate on "linunx/hidden.html", "mac/hidden.html" and "windows/hidden.html" => works fine

[Deashow]

Uploaded a temporary solution for the warning "unknown image" but it didn't solve our main problem for all images.

[Deashow]

Fixing some critical path issues because the "include" was doubled for different files.

[Deashow]

nitrokey-documentation/storage/linux/openvpn-easyrsa.rst:388: WARNING: Could not lex literal_block as "bash". Highlighting skipped.

The problem was it was "code-block bash" but without correct terminal/shell syntax. So i changed "bash" into "none" which solved the highlighting warning.

[Deashow]

Got it "code-block:: none" (line 388-397) is deleted and could be merged.