github: add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,138 @@
+# Contributing to gyp.js
+
+This document will guide you through the contribution process.
+
+### Step 1: Fork
+
+Fork the project [on GitHub](https://github.com/indutny/gyp.js) and check out
+your copy locally.
+
+```text
+$ git clone [email protected]:username/gyp.js.git
+$ cd gyp.js
+$ git remote add upstream git://github.com/indutny/gyp.js.git
+```
+
+#### Which branch?
+
+For developing new features and bug fixes, the `master` branch should be pulled
+and built upon.
+
+### Step 2: Branch
+
+Create a feature branch and start hacking:
+
+```text
+$ git checkout -b my-feature-branch -t origin/master
+```
+
+### Step 3: Commit
+
+Make sure git knows your name and email address:
+
+```text
+$ git config --global user.name "J. Random User"
+$ git config --global user.email "[email protected]"
+```
+
+Writing good commit logs is important. A commit log should describe what
+changed and why. Follow these guidelines when writing one:
+
+1. The first line should be 50 characters or less and contain a short
+   description of the change prefixed with the name of the changed
+   subsystem (e.g. "net: add localAddress and localPort to Socket").
+2. Keep the second line blank.
+3. Wrap all other lines at 72 columns.
+
+A good commit log can look something like this:
+
+```
+subsystem: explaining the commit in one line
+
+Body of commit message is a few lines of text, explaining things
+in more detail, possibly giving some background about the issue
+being fixed, etc. etc.
+
+The body of the commit message can be several paragraphs, and
+please do proper word-wrap and keep columns shorter than about
+72 characters or so. That way `git log` will show things
+nicely even when it is indented.
+```
+
+The header line should be meaningful; it is what other people see when they
+run `git shortlog` or `git log --oneline`.
+
+Check the output of `git log --oneline files_that_you_changed` to find out
+what subsystem (or subsystems) your changes touch.
+
+If your patch fixes an open issue, you can add a reference to it at the end
+of the log. Use the `Fixes:` prefix and the full issue URL. For example:
+
+```
+Fixes: https://github.com/indutny/gyp.js/issues/1337
+```
+
+### Step 4: Rebase
+
+Use `git rebase` (not `git merge`) to sync your work from time to time.
+
+```text
+$ git fetch upstream
+$ git rebase upstream/master
+```
+
+
+### Step 5: Test
+
+Bug fixes and features **should come with tests**. Add your tests in the
+`test/parallel/` directory. For guidance on how to write a test for the gyp.js
+project, see this [guide](./doc/guides/writing_tests.md). Looking at other tests
+to see how they should be structured can also help.
+
+```text
+$ npm install && npm test
+```
+
+Make sure the linter is happy and that all tests pass. Please, do not submit
+patches that fail either check.
+
+### Step 6: Push
+
+```text
+$ git push origin my-feature-branch
+```
+
+Go to https://github.com/yourusername/gyp.js and select your feature branch.
+Click the 'Pull Request' button and fill out the form.
+
+Pull requests are usually reviewed within a few days. If there are comments
+to address, apply your changes in a separate commit and push that to your
+feature branch. Post a comment in the pull request afterwards; GitHub does
+not send out notifications when you add commits.
+
+<a id="developers-certificate-of-origin"></a>
+## Developer's Certificate of Origin 1.1
+
+By making a contribution to this project, I certify that:
+
+* (a) The contribution was created in whole or in part by me and I
+  have the right to submit it under the open source license
+  indicated in the file; or
+
+* (b) The contribution is based upon previous work that, to the best
+  of my knowledge, is covered under an appropriate open source
+  license and I have the right under that license to submit that
+  work with modifications, whether created in whole or in part
+  by me, under the same open source license (unless I am
+  permitted to submit under a different license), as indicated
+  in the file; or
+
+* (c) The contribution was provided directly to me by some other
+  person who certified (a), (b) or (c) and I have not modified
+  it.
+
+* (d) I understand and agree that this project and the contribution
+  are public and that a record of the contribution (including all
+  personal information I submit with it, including my sign-off) is
+  maintained indefinitely and may be redistributed consistent with
+  this project or the open source license(s) involved.