[AssetMapper] Fixing path

[ThomasLandauer]

If the section starts with the pagerfanta CSS, it should use it throughout... :-)

[javiereguiluz]

Good catch, thanks Thomas.

[smnandre]

Could you revert this PR ? @javiereguiluz @ThomasLandauer

The example of missing path was correct before (a non-bundle package with some asset outside the defined path, and the configuration example followed perfectly the given situation "if you get an error like this..."). I highlighted it in green in the end of this message.

Moreover, this change gives the false impression you may need to register asset path for pagerfanta.

But Pagerfanta, as a bundle with default asset management, does not need to register its path.

It is explained just the paragraph before.

---

However, if you get an error like this:
+    The "app" importmap entry contains the path "vendor/some/package/assets/foo.js"
    but it does not appear to be in any of your asset paths.
It means that you're pointing to a valid file, but that file isn't in any of
your asset paths. You can fix this by adding the path to your ``asset_mapper.yaml``
file:
.. code-block:: yaml
    # config/packages/asset_mapper.yaml
    framework:
        asset_mapper:
            paths:
                - assets/
+                - vendor/some/package/assets
-                - vendor/babdev/pagerfanta-bundle/Resources/public/css/

[OskarStark]

Done