Added configuration for build_sphinx command to simplify building

--HG--
branch : distribute
extra : rebase_source : 69ea754fdb336feb1016db3f5ab018e648f38097

setup.cfg

@@ -7,5 +7,10 @@ release = egg_info -RDb ''
 source = register sdist binary
 binary = bdist_egg upload --show-response
 
+[build_sphinx]
+source-dir = docs/
+build-dir = docs/build
+all_files = 1
+
 [upload_docs]
 upload-dir = docs/build/html
\ No newline at end of file