chore(doc): Fix module descriptions for length_prefix_encoding

There's a more complete module description for the encoder and decoder now. Both versions get appended by rustdoc, which looks wrong and shouldn't be necessary.

util/src/length_prefix_encoding/mod.rs

@@ -1,4 +1,2 @@
-/// Module that handles decoding functionality
 pub mod decoder;
-/// Module that handles encoding functionality
 pub mod encoder;