Update README.md and add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,62 @@
+# How to contribute #
+
+We'd love to accept your patches and contributions to this project.  There are
+a just a few small guidelines you need to follow.
+
+
+## Contributor License Agreement ##
+
+Contributions to any Google project must be accompanied by a Contributor
+License Agreement.  This is not a copyright **assignment**, it simply gives
+Google permission to use and redistribute your contributions as part of the
+project.
+
+  * If you are an individual writing original source code and you're sure you
+    own the intellectual property, then you'll need to sign an [individual
+    CLA][].
+
+  * If you work for a company that wants to allow you to contribute your work,
+    then you'll need to sign a [corporate CLA][].
+
+You generally only need to submit a CLA once, so if you've already submitted
+one (even if it was for a different project), you probably don't need to do it
+again.
+
+[individual CLA]: https://developers.google.com/open-source/cla/individual
+[corporate CLA]: https://developers.google.com/open-source/cla/corporate
+
+
+## Submitting a patch ##
+
+  1. It's generally best to start by opening a new issue describing the bug or
+     feature you're intending to fix.  Even if you think it's relatively minor,
+     it's helpful to know what people are working on.  Mention in the initial
+     issue that you are planning to work on that bug or feature so that it can
+     be assigned to you.
+
+  1. Follow the normal process of [forking][] the project, and setup a new
+     branch to work in.  It's important that each group of changes be done in
+     separate branches in order to ensure that a pull request only includes the
+     commits related to that bug or feature.
+
+  1. Do your best to have [well-formed commit messages][] with a [good
+     description][] for each change.  This provides consistency throughout
+     the project, and ensures that commit messages are able to be formatted
+     properly by various git tools.
+
+  1. Keep PRs [small and focused][] on a single issue.  Do not make unrelated
+     changes in the same PR "because you're there"; this includes reformatting
+     of code, whether automatically or manually.
+
+  1. Finally, push the commits to your fork and submit a [pull request][].
+
+[forking]: https://help.github.com/articles/fork-a-repo
+[well-formed commit messages]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
+[good description]: https://google.github.io/eng-practices/review/developer/cl-descriptions.html
+[pull request]: https://help.github.com/articles/creating-a-pull-request
+[small and focused]: https://google.github.io/eng-practices/review/developer/small-cls.html
+
+
+## Style ##
+
+Contributions should follow the [Go Style Guide](https://google.github.io/styleguide/go).  Code should be [formatted] with `gofmt`.

README.md

@@ -195,6 +195,7 @@ S2ConvexHull         | ✅
 S2CrossingEdge       | ✅
 S2HausdorffDistance  | ❌
 S2ShapeNesting       | ❌
+S2ValidationQuery    | ❌
 
 ### Supporting Types
 
@@ -203,32 +204,37 @@ C++ Type                         | Go
 S2BooleanOperation               | ❌
 S2BufferOperation                | ❌
 S2Builder                        | ❌
-S2BuilderClosedSetNormalizer     | ❌
-S2BuilderFindPolygonDegeneracies | ❌
 S2BuilderGraph                   | ❌
-S2BuilderLayers                  | ❌
-S2BuilderSnapFunctions           | ❌
-S2BuilderTesting                 | ❌
-S2Builderutil\*                  | ❌
+S2BuilderLayer                   | ❌
+S2BuilderUtil_\*                 | ❌
+S2CellIterator                   | ❌
+S2CellIteratorJoin               | ❌
+S2CellRangeIterator              | ❌
 S2Coder                          | ❌
+S2Earth                          | ❌
 S2EdgeClipping                   | ✅
 S2EdgeCrosser                    | ✅
 S2EdgeCrossings                  | ✅
 S2EdgeDistances                  | ✅
 S2EdgeTessellator                | ✅
+S2Fractal                        | ❌
 S2LoopMeasures                   | ❌
 S2Measures                       | ✅
 S2MemoryTracker                  | ❌
 S2Metrics                        | ❌
 S2PointUtil                      | 🟡
+S2PointCompression               | 🟡
 S2PolygonBuilder                 | ❌
 S2PolylineAlignment              | ❌
 S2PolylineMeasures               | ✅
 S2PolylineSimplifier             | ❌
 S2Predicates                     | ✅
 S2Projections                    | ❌
-S2rectBounder                    | ❌
+S2Random                         | ❌
+S2RectBounder                    | ❌
+S2RegionSharder                  | ❌
 S2RegionTermIndexer              | ❌
+S2ShapeIndexBufferedRegion       | ❌
 S2ShapeIndexMeasures             | ❌
 S2ShapeIndexUtil\*               | 🟡
 S2ShapeMeasures                  | ❌
@@ -239,7 +245,13 @@ S2TextFormat                     | ✅
 S2WedgeRelations                 | ✅
 S2WindingOperation               | ❌
 
+
 ### Encode/Decode
 
 Encoding and decoding of S2 types is fully implemented and interoperable with
 C++ and Java.
+
+
+## Disclaimer
+
+This is not an official Google product.