Spellcheck our public headers.

Also fix some formatting.

Change-Id: I8fb1a95d4a55e40127433f0114fd08a82a4c3d41
Reviewed-on: https://boringssl-review.googlesource.com/13103
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/ecdsa.h b/include/openssl/ecdsa.h
index f6e9982..3890744 100644
--- a/include/openssl/ecdsa.h
+++ b/include/openssl/ecdsa.h
@@ -66,7 +66,7 @@
  * Algorithm over elliptic curves. */
 
 
-/* Signing and verifing. */
+/* Signing and verifying. */
 
 /* ECDSA_sign signs |digest_len| bytes from |digest| with |key| and writes the
  * resulting signature to |sig|, which must have |ECDSA_size(key)| bytes of
@@ -80,7 +80,7 @@
 /* ECDSA_verify verifies that |sig_len| bytes from |sig| constitute a valid
  * signature by |key| of |digest|. (The |type| argument should be zero.) It
  * returns one on success or zero if the signature is invalid or an error
- * occured. */
+ * occurred. */
 OPENSSL_EXPORT int ECDSA_verify(int type, const uint8_t *digest,
                                 size_t digest_len, const uint8_t *sig,
                                 size_t sig_len, EC_KEY *key);