Move Coding style from wiki to main repo.

This is the last page to migrate, which enables disabling the wiki completely.

Add links to markdown google style guide.

[email protected]
BUG=

Review-Url: https://codereview.chromium.org/2017433002

CODING_STYLE.md

@@ -0,0 +1,80 @@
+# Coding style
+
+For Markdown, use the [Google
+style](https://github.com/google/styleguide/blob/gh-pages/docguide/style.md).
+
+
+## General style
+
+*   ALL_CAPS_GLOBALS at top
+*   function_name
+*   ClassName
+*   variable_name
+*   +2 space indent, a legacy from Google
+*   2 empty lines between file level symbols
+*   1 empty line between class members
+
+
+## Line breaks
+
+Keep line width under 80 chars. Break a line on a first syntactic structure,
+prefer hanging indent of 4 spaces over vertical alignment. Prefer parentheses
+for line joining over `\`. For JSON-like nested dicts and lists it's acceptable
+to use 2 space indent.
+
+Yes:
+
+    str = (
+        'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam diam met, '
+        'tristique ac placerat sit amet: %s, %s' % (a, b))
+
+    func_call(
+        param1=...,
+        param2=...,
+        param3=...)
+
+    like_json = {
+      'key': {
+        'a': {
+          'b': 123,
+          'c': 123,
+          'd': 123,
+        },
+      },
+    }
+
+No:
+
+    str = \
+        'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam diam met, '
+
+    str = ('Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam diam '
+           'met, ....')
+
+    func_call(param1=...,
+              param2=...,
+              param3=...)
+
+    fun_call(param1=..., param2=...,
+        param3=...)
+
+
+## Import statements
+
+  * import modules, not symbols.
+  * `from X import Y` statements, then `import X` statements within a single block
+
+
+Separations:
+
+    <import block of stdlib>
+
+    <import block of import sys.path hack, e.g. test_env. Needed for now>
+
+    <import block of appengine lib>
+
+    <import block of appengine third_party lib, e.g. webapp2, or in third_party/>
+
+    <import block of components and other application external libs>
+
+    <import block of application libs>

README.md

@@ -47,6 +47,7 @@ A complete CI toolkit:
 ## Contributing
 
 *   Sign the [Google CLA](https://cla.developers.google.com/clas).
+*   See the [coding style](CODING_STYLE.md).
 *   Make sure your `user.email` and `user.name` are configured in `git config`.
 
 Run the following to setup the code review tool and create your first review: