Add alias name convention to CONTRIBUTING.md (GenericMappingTools#1256)

* Add alias name convention to CONTRIBUTING.md

* Update CONTRIBUTING.md

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>

Co-authored-by: Wei Ji <23487320+weiji14@users.noreply.github.com>

Author: 2 people

CONTRIBUTING.md

@@ -219,7 +219,7 @@ General guidelines for pull requests (PRs):
   do.
 * Each pull request should consist of a **small** and logical collection of changes.
 * Larger changes should be broken down into smaller components and integrated
-  separately.
+  separately. For example, break the wrapping of aliases into multiple pull requests.
 * Bug fixes should be submitted in separate PRs.
 * Use underscores for all Python (*.py) files as per [PEP8](https://www.python.org/dev/peps/pep-0008/),
   not hyphens. Directory names should also use underscores instead of hyphens.
@@ -303,6 +303,12 @@ warn us and you can make a new commit with the formatted code.
 Even better, you can just write `/format` in the first line of any comment in a
 Pull Request to lint the code automatically.
 
+When wrapping a new alias, use an underscore to separate words bridged by vowels
+(aeiou), such as `no_skip` and `z_only`. Do not use an underscore to separate
+words bridged only by consonants, such as `distcalc`, and `crossprofile`. This
+convention is not applied by the code checking tools, but the PyGMT maintainers
+will comment on any pull requests as needed.
+
 We also use [flake8](http://flake8.pycqa.org/en/latest/) and
 [pylint](https://www.pylint.org/) to check the quality of the code and quickly catch
 common errors.