Original commit message from CVS:

* docs/README:
* docs/images/gdp-header.svg:
add a gdp image
* docs/libs/Makefile.am:
* docs/libs/gdp-header.png:
* libs/gst/dataprotocol/dataprotocol.c:
add it to the API docs
* docs/manual/intro-motivation.xml:
fix typo