Update contributing guidelines.

* Align CONTRIBUTING.md with the google/new-project template.
* Explain the support story for the CMake config.

PiperOrigin-RevId: 421120645

CONTRIBUTING.md

@@ -1,36 +1,31 @@
-# Contributing
+# How to Contribute
 
-We'd love to accept your code patches! However, before we can take them, we
-have to jump a couple of legal hurdles.
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
 
-## Contributor License Agreements
+## Contributor License Agreement
 
-Please fill out either the individual or corporate Contributor License
-Agreement as appropriate.
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
 
-* If you are an individual writing original source code and you're sure you
-own the intellectual property, then sign an [individual CLA](https://developers.google.com/open-source/cla/individual).
-* If you work for a company that wants to allow you to contribute your work,
-then sign a [corporate CLA](https://developers.google.com/open-source/cla/corporate).
+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.
 
-Follow either of the two links above to access the appropriate CLA and
-instructions for how to sign and return it.
+## Code Reviews
 
-## Submitting a Patch
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
 
-1. Sign the contributors license agreement above.
-2. Decide which code you want to submit. A submission should be a set of changes
-that addresses one issue in the [issue tracker](https://github.com/google/leveldb/issues).
-Please don't mix more than one logical change per submission, because it makes
-the history hard to follow. If you want to make a change
-(e.g. add a sample or feature) that doesn't have a corresponding issue in the
-issue tracker, please create one.
-3. **Submitting**: When you are ready to submit, send us a Pull Request. Be
-sure to include the issue number you fixed and the name you used to sign
-the CLA.
+See [the README](README.md#contributing-to-the-leveldb-project) for areas
+where we are likely to accept external contributions.
 
-## Writing Code ##
+## Community Guidelines
 
-If your contribution contains code, please make sure that it follows
-[the style guide](https://google.github.io/styleguide/cppguide.html).
-Otherwise we will have to ask you to make changes, and that's no fun for anyone.
+This project follows [Google's Open Source Community
+Guidelines](https://opensource.google/conduct/).

README.md

@@ -99,6 +99,12 @@ Contribution requirements:
    clang-format -i --style=file <file>
    ```
 
+We are unlikely to accept contributions to the build configuration files, such
+as `CMakeLists.txt`. We are focused on maintaining a build configuration that
+allows us to test that the project works in a few supported configurations
+inside Google. We are not currently interested in supporting other requirements,
+such as different operating systems, compilers, or build systems.
+
 ## Submitting a Pull Request
 
 Before any pull request will be accepted the author must first sign a