more documentation and cleanups for various modules.

1 files changed, 14 insertions, 0 deletions

diff --git a/registry/README b/registry/README
index b455809406a7..914db30a2f01 100644
--- a/registry/README
+++ b/registry/README
@@ -1 +1,15 @@
 Registry reading, etc.
+
+This provides tools for dealing with the legacy binary types database
+format, still in use by extensions and the core code. While the actual
+binary file format is implemented by the [[store]] code, the wrapper
+that turns this into a type registry is implemented here.
+
+While this code is primarily used in only two modes:
+
+* linear write / concatenate
+* random access read
+
+The API unfortunately exposes a random-access write approach, which -
+while ~unused needs before we can re-write this away from the store
+backend.