Added contribution rules in README

README.md

@@ -58,6 +58,34 @@ Sample tests can be found in the [sample directory][samples].
 * [Tests with signals][sample-signal]
 * [Using report hooks][sample-report]
 
+## Contributing
+
+Contributions are welcomed, but must follow a simple set of rules in order to
+be merged.
+
+**Please follow these conventions if you want your pull request(s) accepted.**
+
+### General
+
+* Use 4 (four) spaces for indentation.
+* No trailing whitespaces.
+* 80 chars column limit.
+* No trash files. Trash files are by-products of the compilation process, or
+  generated files that does not need to be under version control.
+* Pull requests must compile and work properly.
+* Pull requests must be mergeable automatically.
+* Number of commits in a pull request should be kept to one commit and all
+  additional commits must be squashed.
+* You may have more than one commit in a pull request if the commits are
+  separate changes, otherwise squash them.
+
+### Translations
+
+* You can contribute new translation files for output messages, on the
+  condition that you are fluent with the language itself.
+* Each correction on existing translations must be followed by a
+  rationale ("why would the translation be better if the change is applied?")
+
 ## F.A.Q.
 
 **Q. What's wrong with other test frameworks?**