Fix some typos in documentation and comments
diff --git a/library/ecdh.c b/library/ecdh.c
index eaad62c..80e9676 100644
--- a/library/ecdh.c
+++ b/library/ecdh.c
@@ -43,7 +43,7 @@
* Generate public key (restartable version)
*
* Note: this internal function relies on its caller preserving the value of
- * the output parameter 'd' accross continuation calls. This would not be
+ * the output parameter 'd' across continuation calls. This would not be
* acceptable for a public function but is OK here as we control call sites.
*/
static int ecdh_gen_public_restartable( mbedtls_ecp_group *grp,