add docs to build

add docs to build

Original commit message from CVS:
* Makefile.am:
* configure.ac:
add docs to build
* common/plugins.xsl:
wrap Description into a refsect2
* docs/Makefile.am:
* docs/plugins/Makefile.am:
* docs/plugins/gst-plugins-good-plugins-docs.sgml:
* docs/plugins/gst-plugins-good-plugins-sections.txt:
* gst/goom/Makefile.am:
* gst/goom/gstgoom.c: (gst_goom_get_type), (gst_goom_base_init),
(gst_goom_class_init), (gst_goom_init), (gst_goom_dispose),
(gst_goom_sink_setcaps), (gst_goom_src_setcaps),
(gst_goom_src_negotiate), (gst_goom_event), (gst_goom_chain),
(gst_goom_change_state):
* gst/goom/gstgoom.h:
GstGOOM -> GstGoom
add an example launch line
* gst/level/gstlevel.h:
* gst/monoscope/gstmonoscope.c:
cleanups