Docstring: explain version-checking script

This documents the general behavior and expectations of the
version-checking CI script.

test/check_configurable_requirements.py

@@ -1,3 +1,19 @@
+"""
+This script performs syntax analysis on the volatility3 source tree through a combination of AST analysis and import-time introspection of classes.
+
+The current checks it implements are:
+    1. Ensure that classes derived from `ConfigurableInterface` properly
+    declare all `VersionableInterface` classes that they make use of in their
+    `get_requirements()` classmethod.
+
+    :WARNING: a notable exception to this are classes defined within factory
+    functions. Because these classes are not created until the factory function
+    is called, they therefore do no exist at import time and cannot be checked
+    by this script. It is important to keep in mind during code review that
+    this is a best-effort check and does not make guarantees about the
+    completeness of declared requirements.
+"""
+
 import argparse
 import ast
 import importlib