DOC: Add PR tags and licensing to CONTRIBUTING.md

Author: effigies

CONTRIBUTING.md

@@ -54,6 +54,11 @@ It can also be helpful to test your changes locally, using an [FMRIPREP developm
 
 A member of the development team will review your changes to confirm that they can be merged into the main codebase.
 
+Pull requests titles should begin with a descriptive prefix: ``ENH`` (enhancement), ``FIX`` (bug fix), ``TST`` (testing),
+``DOC`` (documentation), ``STY`` (style), ``REF`` (refactor), ``CI`` (continous integration), ``MAINT`` (maintenance).
+For example, `[ENH] Support for SB-reference in multi-band datasets`.
+For works-in-progress, add the ``WIP`` tag in addition to the descriptive prefix.
+Pull-requests tagged with ``[WIP]`` will not merged in until the tag is removed.
 
 ## FMRIPREP coding style guide
 
@@ -105,6 +110,11 @@ We welcome and recognize all contributions from documentation to testing to code
 You can see a list of current contributors in our [zenodo file][link_zenodo].
 If you are new to the project, don't forget to add your name and affiliation there!
 
+## Licensing
+
+fMRIPrep is licensed under the BSD 3-clause license. Any contributions will be licensed under
+the same terms.
+
 ## Thank you!
 
 You're awesome. :wave::smiley: