docs/plugins/: Updates; update inspect info for rtpmanager => gstrtpmanager rename, hopefully that makes the build bo...

Original commit message from CVS:
* docs/plugins/gst-plugins-bad-plugins.args:
* docs/plugins/gst-plugins-bad-plugins.signals:
* docs/plugins/inspect/plugin-dtsdec.xml:
* docs/plugins/inspect/plugin-gstrtpmanager.xml:
* docs/plugins/inspect/plugin-musepack.xml:
* docs/plugins/inspect/plugin-rtpmanager.xml:
* docs/plugins/inspect/plugin-sdl.xml:
* docs/plugins/inspect/plugin-spcdec.xml:
* docs/plugins/inspect/plugin-swfdec.xml:
Updates; update inspect info for rtpmanager => gstrtpmanager rename,
hopefully that makes the build bots happy again.