docs/plugins/: Now we have full hierarchy.

docs/plugins/: Now we have full hierarchy.

Original commit message from CVS:
* docs/plugins/Makefile.am:
* docs/plugins/gst-plugins-bad-plugins-sections.txt:
* docs/plugins/gst-plugins-bad-plugins.args:
* docs/plugins/gst-plugins-bad-plugins.hierarchy:
* docs/plugins/gst-plugins-bad-plugins.interfaces:
* docs/plugins/gst-plugins-bad-plugins.prerequisites:
* docs/plugins/gst-plugins-bad-plugins.signals:
Now we have full hierarchy.
* docs/plugins/inspect/plugin-metadata.xml:
Regenerate.
* ext/amrwb/gstamrwbdec.h:
Add doc blob for object instance.