Fix formatting of code examples in plugin documentation

It is not necessary to indent code samples that are inside
the [source] section markers.  The prettifier will include the
indendation automatically in the rendered html.

Some of the code samples in the plugin documentation still have
the unnecessary indentation, so remove it.

Change-Id: I8fc870a3d1e8deb0919c13abbb00bd48b7f087f8
1 file changed