Add installation and repository sections to documentation.
Add installation and repository sections to documentation.

akash1808/wrapt,ionelmc/python-lazy-object-proxy,pombredanne/wrapt,ionelmc/python-lazy-object-proxy,pombredanne/wrapt,GrahamDumpleton/wrapt,pombredanne/python-lazy-object-proxy,pombredanne/python-lazy-object-proxy,github4ry/wrapt,linglaiyao1314/wrapt,wujuguang/wrapt,linglaiyao1314/wrapt,wujuguang/wrapt,GrahamDumpleton/wrapt,github4ry/wrapt,akash1808/wrapt