Rename spec files to not have numbers everywhere; update targets.yaml

specification/modules/end_to_end_encryption.rst

@@ -0,0 +1,15 @@
+End-to-End Encryption
+=====================
+
+.. TODO-doc
+  - Why is this needed.
+  - Overview of process
+  - Implementation
+
+Matrix optionally supports end-to-end encryption, allowing rooms to be created
+whose conversation contents is not decryptable or interceptable on any of the
+participating homeservers.
+
+End-to-end crypto is still being designed and prototyped - notes on the design
+may be found at https://lwn.net/Articles/634144/
+