Fix typo in SHA512 documentation
diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index bf40e4b..34a90b5 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -272,7 +272,7 @@
* \param ilen The length of the input data in Bytes.
* \param output The SHA-384 or SHA-512 checksum result. This must
* be a writable buffer of length \c 64 Bytes.
- * \param is384 Determines which function to use. This must be eiher
+ * \param is384 Determines which function to use. This must be either
* \c 0 for SHA-512, or \c 1 for SHA-384.
*/
MBEDTLS_DEPRECATED void mbedtls_sha512( const unsigned char *input,