doc: Update the list of files to ignore
doc: Update the list of files to ignore

Another list to maintain by hand. We could split the variables declaring
the source files into private and public header in a separate Makefile
and then include it from both doc/reference/cogl/Makefile and
cogl/Makefile, but I'll leave this for the next person to look at the
documentation.

djdeath/cogl,gcampax/cogl,djdeath/cogl-android,gcampax/cogl,gcampax/cogl,djdeath/cogl,djdeath/cogl-android,djdeath/cogl-android,djdeath/cogl,gcampax/cogl