docs: Fix typo (#4813)

Signed-off-by: Per Lundberg <perlun@gmail.com>

Mirrored from https://github.com/envoyproxy/envoy @ d25a0a50d829f3f638f4840ff5c9fedc18835408

envoy/config/filter/http/ext_authz/v2alpha/ext_authz.proto

@@ -32,7 +32,7 @@ message ExtAuthz {
   }
 
   // The filter's behaviour in case the external authorization service does
-  // not respond back. When it is set to true, Envoy will also allow traffic in case of
+  // not respond back. When set to true, Envoy will also allow traffic in cases when
   // an error occurs during the authorization process.
   // Defaults to false.
   bool failure_mode_allow = 2;
@@ -45,7 +45,7 @@ message ExtAuthz {
 // A successful check allows the authorization service adding or overriding headers from the
 // original request before dispatching it to the upstream. This is done by configuring which headers
 // in the authorization response should be sent to the upstream. See *allowed_authorization_headers*
-// bellow.
+// below.
 //
 // A failed check will cause this filter to close the HTTP request with 403 (Forbidden),
 // unless a different status code has been indicated by the authorization server via response