Add missing doc comments & enable missing_docs lint.

src/digest.rs

@@ -68,6 +68,7 @@ pub struct Context {
     pending: [u8; MAX_BLOCK_LEN],
     num_pending: usize,
 
+    /// The context's algorithm.
     pub algorithm: &'static Algorithm,
 }
 

src/hmac.rs

@@ -1,4 +1,4 @@
-// Copyright 2015 Brian Smith.
+// Copyright 2015-2016 Brian Smith.
 //
 // Permission to use, copy, modify, and/or distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above
@@ -218,6 +218,7 @@ impl SigningKey {
         key
     }
 
+    /// The digest algorithm for the key.
     pub fn digest_algorithm(&self) -> &'static digest::Algorithm {
         self.ctx_prototype.inner.algorithm()
     }

src/lib.rs

@@ -30,7 +30,6 @@
 #![allow(
     missing_copy_implementations,
     missing_debug_implementations,
-    missing_docs, // TODO
 )]
 #![deny(
     const_err,
@@ -41,6 +40,7 @@
     fat_ptr_transmutes,
     improper_ctypes,
     match_of_unit_variant_via_paren_dotdot,
+    missing_docs,
     mutable_transmutes,
     no_mangle_const_items,
     non_camel_case_types,