Minor doc improvements

README.md

 gae: A Google AppEngine SDK wrapper designed for testing+extensibility (for Go)
 ===================
 
 [![GoDoc](https://godoc.org/github.com/luci/gae?status.svg)](https://godoc.org/github.com/luci/gae)
 [![Build Status](https://travis-ci.org/luci/gae.svg?branch=master)](https://travis-ci.org/luci/gae)
 [![Coverage Status](https://coveralls.io/repos/luci/gae/badge.svg?branch=master&service=github)](https://coveralls.io/github/luci/gae?branch=master)
 
-
 Installing
 ----------
 
     go get -u github.com/luci/gae/...
 
+Why/What/How
+------------
 
-Code layout
------------
-
-  * This directory contains the interfaces common to all supported services.
-  * [/dummy/...](https://github.com/luci/gae/tree/master/dummy)
-    Contains dummy service implementations (they just panic, not too interesting).
-  * [/prod/...](https://github.com/luci/gae/tree/master/prod)
-    Contains service implementations based on the [Appengine SDK](google.golang.org/appengine/datastore).
-  * [/memory/...](https://github.com/luci/gae/tree/master/memory)
-    Contains fast, in-memory service implementations for testing.
-  * [/filters/...](https://github.com/luci/gae/tree/master/filters)
-    Contains optional service filters to transparently change the behavior
-    of the services. Can be used with any service implementation.
-  * [/helper/...](https://github.com/luci/gae/tree/master/helper) contains
-    methods for doing helpful reflection, binary serialization, etc. You
-    don't have to worry about these too much, but they're there if you need
-    them for doing lower-level things (like building new service implementations
-    or filters).
-
+See the [godocs](https://godoc.org/github.com/luci/gae).
 
 Versioning
 ----------
 
   * Branch `master` constains the latest code.
 
-
 Contributing
 ------------
 
   * Sign the [Google CLA](https://cla.developers.google.com/clas).
   * Make sure your `user.email` and `user.name` are configured in `git config`.
   * Install the [pcg](https://github.com/maruel/pre-commit-go) git hook:
     `go get -u github.com/maruel/pre-commit-go/cmd/... && pcg`
 
 Run the following to setup the code review tool and create your first review:
 
     git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git $HOME/src/depot_tools
     export PATH="$PATH:$HOME/src/depot_tools"
     cd $GOROOT/github.com/luci/gae
     git new-branch work
     # or `git checkout -b work origin/master` if you like typing more.
 
     # hack hack
 
     git commit -a -m "This is awesome\nR=joe@example.com"
     # This will ask for your Google Account credentials.
     git cl upload -s
     # Wait for LGTM over email.
     git cl land
 
 Use `git cl help` and `git cl help <cmd>` for more details.