Tidy bssl-crypto documentation

This probably needs a few iterations, but fix the stuff I noticed on a
first pass:

- I don't think it's useful to say this is the BoringSSL implementation
  of something. That's all implicit from this crate anyway.

- Rust seems to prefer "Returns ..." rather than "Return ..."

- Algorithm names like "hkdf" or "hmac" should be written "HKDF" or
  "HMAC" when referring to the algorithms. Also BoringSSL is styled
  "BoringSSL" rather than "boringssl".

- Given Rust overall doesn't try to handle allocation failure, let's
  just write that we don't believe in allocation failure once in the
  README rather than marking which functions do and don't panic.

Change-Id: I48501717dd0b063a2fa4106c4c140d76a7ef69a9
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/60546
Reviewed-by: Nabil Wadih <nwadih@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
diff --git a/rust/bssl-crypto/src/lib.rs b/rust/bssl-crypto/src/lib.rs
index 2c80ae8..ce9500b 100644
--- a/rust/bssl-crypto/src/lib.rs
+++ b/rust/bssl-crypto/src/lib.rs
@@ -22,26 +22,26 @@
     clippy::expect_used
 )]
 
-//! Rust boringssl binding
+//! Rust BoringSSL bindings
 
 extern crate core;
 
-/// BoringSSL implemented plain aes operations.
+/// AES block operations.
 pub mod aes;
 
-/// BoringSSL implemented hash functions.
+/// Hash functions.
 pub mod digest;
 
-/// BoringSSL implemented Ed25519 operations.
+/// Ed25519, a signature scheme.
 pub mod ed25519;
 
-/// BoringSSL implemented hkdf operations.
+/// HKDF, a hash-based key derivation function.
 pub mod hkdf;
 
-/// BoringSSL implemented hmac operations.
+/// HMAC, a hash-based message authentication code.
 pub mod hmac;
 
-/// BoringSSL implemented cryptographically secure pseudo-random number generation.
+/// Random number generation.
 pub mod rand;
 
 #[cfg(test)]