cursory documentation of pre-commit

BUILDING.md

@@ -85,3 +85,21 @@ Example:
 
 If your port/build includes `arm-none-eabi-gdb-py`, consider using it instead, as it can be used for better register
 debugging with https://github.com/bnahill/PyCortexMDebug
+
+# Code Quality Checks
+
+We apply code quality checks using pre-commit.  Install pre-commit once per system with
+
+    python3 -mpip install pre-commit
+
+Activate it once per git clone with
+
+    pre-commit --install
+
+Pre-commit also requires some additional programs to be installed through your package manager:
+
+ * Standard Unix tools such as make, find, etc
+ * The gettext package, any modern version
+ * uncrustify version 0.71 (0.72 is also tested)
+
+Some pre-commit quality checks require your active attention to resolve, others (such as the formatting checks of uncrustify) are made automatically and must simply be incorporated into your code changes by committing them.