tf.learn: Clean up documentation, remove contrib/learn/g3doc and move it to g3doc/contrib/learn. Add api docs for learn (need more work).

Change: 120399615

Author: ilblackdragon

tensorflow/contrib/learn/g3doc/api_docs/python/index.md

@@ -32,7 +32,7 @@ Returns the file system schemes registered for this Env .
 
 
 
-#### `void tensorflow::Env::RegisterFileSystem(const string &scheme, FileSystemRegistry::Factory factory)` {#void_tensorflow_Env_RegisterFileSystem}
+#### `Status tensorflow::Env::RegisterFileSystem(const string &scheme, FileSystemRegistry::Factory factory)` {#Status_tensorflow_Env_RegisterFileSystem}