PEP 751: mention dependency groups for services to look for (#4290)

Author: brettcannon

peps/pep-0751.rst

@@ -135,11 +135,17 @@ e.g.:
   if len(filename) > 11 and filename.startswith("pylock.") and filename.endswith(".toml"):
       name = filename.removeprefix("pylock.").removesuffix(".toml")
 
-The expectation is that services that install lock files automatically will
-search for a lock file with the service's name, then fallback to the generic
-``pylock.toml`` (e.g. a cloud host service named Spam would first look for
-``pylock.spam.toml`` to install, and if that file didn't exist then install from
-``pylock.toml``).
+The expectation is that services that automatically install from lock files will
+search for:
+
+1. The lock file with the service's name and doing the default install
+2. A multi-use ``pylock.toml`` with a dependency group with the name of the service
+3. The default install of ``pylock.toml``
+
+E.g. a cloud host service named "spam" would first look for
+``pylock.spam.toml`` to install from, and if that file didn't exist then install
+from ``pylock.toml`` and look for a dependency group named "spam" fo use if
+present.
 
 The lock file(s) SHOULD be located in the directory as appropriate for the scope
 of the lock file. Locking against a single ``pyproject.toml``, for instance,