[Bug]: Relative paths for Literalincludes in included files are resolved incorretly

[linawolf]

Summary

Relative paths are resolved from the location where the file is included not from the location oft the file itself

Code snippet that reproduces the problem

I have the following directory structures:

They are all included in Index.rst

Now if one of the properties or examples has a literalinclude using relativ paths I would expect the following to work:

..  literalinclude:: ../_CodeSnippets/_creationOptions.php
    :language: php
    :caption: EXT:my_extension/Configuration/TCA/Overrides/tt_content.php

But have to do

..  literalinclude:: _CodeSnippets/_creationOptions.php
    :language: php
    :caption: EXT:my_extension/Configuration/TCA/Overrides/tt_content.php

Or an absolute path like

..  literalinclude:: /Types/_CodeSnippets/_creationOptions.php
    :language: php
    :caption: EXT:my_extension/Configuration/TCA/Overrides/tt_content.php

Expected output

I would expect

..  literalinclude:: ../_CodeSnippets/_creationOptions.php
    :language: php
    :caption: EXT:my_extension/Configuration/TCA/Overrides/tt_content.php

To work