Add a CONTRIBUTING.md file

Closes gh-65

Author: rgommers

CONTRIBUTING.md

@@ -0,0 +1,26 @@
+# Contributing to the Array API Standard
+
+Thank you for your interest in contributing!
+
+
+## Contributing 
+
+If you would like to contribute textual clarifications or other "maintenance
+type" changes, please open a pull request on the
+https://github.com/data-apis/array-api repository.
+
+If you would like to add more functionality to the Array API Standard, please
+take note of:
+- the Scope section of the standard
+- the [document outlining the Consortium's Process for standardization](https://github.com/data-apis/governance/blob/master/process_document.md)
+before opening a pull request. If your proposed addition seems in scope,
+opening an issue for discussion may be more appropriate as a first step.
+
+
+## Reporting issues
+
+Please use the [issue tracker](https://github.com/data-apis/array-api/issues)
+for reporting issues with the published Array API Standard. 
+
+Please note that *implementation* issues should be reported to the project
+implementing the standard.