Document meta-python2 dependency in README.
Document meta-python2 dependency in README.

This layer has dependend on the meta-python2 layer since commit
4eb1ab946 ("conf/layer.conf: Add meta-python2 to LAYERDEPENDS"), but this
was not documented in the README.

Signed-off-by: Raphael Kubo da Costa <5fe4d20cf6ab8a2cf4e5e71d4c2d58346e96df0d@intel.com>

OSSystems/meta-browser,schnitzeltony/meta-browser,schnitzeltony/meta-browser,OSSystems/meta-browser,OSSystems/meta-browser,schnitzeltony/meta-browser,schnitzeltony/meta-browser,OSSystems/meta-browser