docs(CONTRIBUTING): add GitHub Issue and PR template

Also about checklist to include new operators

Fixes issues #1355 and #1429

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,21 @@
+<!--
+Thank you for raising your concerns, we appreciate your feedback and contributions to this repository.
+
+Before you continue, consider the following:
+
+If you have a "How do I do ...?" question, it is better for you and for us that this question is placed in [StackOverflow](http://stackoverflow.com/questions/tagged/rxjs5) or some chat channel. This way, you are making it easier for others to learn from your experiences too.
+
+These "Issues" are meant only for technical problems, bugs, and proposals related to the library.
+
+If your issue is a bug, please follow the format below:
+-->
+
+**RxJS version:**
+
+**Code to reproduce:**
+
+**Expected behavior:**
+
+**Actual behavior:**
+
+**Additional information:**

.github/PULL_REQUEST_TEMPLATE.md

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+<!--
+Thank you very much for your pull request!
+
+If your PR is the addition of a new operator, please make sure all these boxes are ticked with an x:
+
+- [ ] Add the operator to either Core or KitchenSink
+- [ ] It must have a `-spec.ts` tests file covering the canonical corner cases, with marble diagram tests
+- [ ] If possible, write a `asDiagram` test case too, for PNG diagram generation purposes
+- [ ] The spec file should have a type definition test at the end of the spec to verify type definition for various use cases
+- [ ] The operator must be documented in JSDoc style in the implementation file, including also the PNG marble diagram image
+- [ ] The operator should be listed in `doc/operators.md` in a category of operators
+- [ ] It should also be inserted in the operator decision tree file `doc/decision-tree-widget/tree.yml`
+- [ ] You may need to update `MIGRATION.md` if the operator differs from the corresponding one in RxJS v4
+-->
+
+**Description:**
+
+**Related issue (if exists):**

doc/operator-creation.md

@@ -128,7 +128,20 @@ There are a few things to know and (try to) understand while developing operator
    the shared underlying subscription.
    - When you `subscribe` to an Observable, the functions or Observer you passed are used to create the final `destination`
    `Subscriber` for the chain. It's this `Subscriber` that is really also the shared `Subscriptoin` for the operator chain.
-
+
+### Submitting a PR for an Operator
+
+Please complete these steps for each new operator added to RxJS as a pull request:
+
+- Add the operator to either Core or KitchenSink
+- It must have a `-spec.ts` tests file covering the canonical corner cases, with marble diagram tests
+- If possible, write a `asDiagram` test case too, for PNG diagram generation purposes
+- The spec file should have a type definition test at the end of the spec to verify type definition for various use cases
+- The operator must be documented in JSDoc style in the implementation file, including also the PNG marble diagram image
+- The operator should be listed in `doc/operators.md` in a category of operators
+- It should also be inserted in the operator decision tree file `doc/decision-tree-widget/tree.yml`
+- You may need to update `MIGRATION.md` if the operator differs from the corresponding one in RxJS v4
+
 ### Inner Subscriptions
 
 An "inner subscriber" or "inner subscription" is any subscription created inside of an operator's primary Subscriber. For example,