DOC: Add new REGTEST tag info about reg testing.
diff --git a/CONTRIBUTING b/CONTRIBUTING
index 9e0d625..b5ba182 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -566,6 +566,9 @@
- LICENSE licensing updates (may impact distro packagers).
+ - REGTEST updates to any of the regression testing files found in reg-tests
+ directory, including README or any documentation file.
+
When the patch cannot be categorized, it's best not to put any type tag, and to
only use a risk or complexity information only as below. This is commonly the