update comment to be lowercase

sharding/config.go

@@ -56,13 +56,13 @@ func (c *Config) ValidateConfig() error {
 type ShardedCopyFilterConfig struct {
 	// Ghostferry requires an index to be present on sharding key to improve the performance of the data iterator's query.
 
-	// `USE` is used by default as part of the index hint i.e. `USE INDEX`.
+	// `use` is used by default as part of the index hint i.e. `USE INDEX`.
 	// `USE INDEX` is taken as a suggestion and optimizer can still opt in to use full table scan if it thinks it's faster.
 	//
-	// `FORCE` replaces `USE INDEX` with `FORCE INDEX` on the query.
+	// `force` replaces `USE INDEX` with `FORCE INDEX` on the query.
 	// `FORCE INDEX` will force the optimizer to use the index and will not consider other options like full table scan.
 	//
-	// `NONE` will not use any index hint.
+	// `none` will not use any index hint.
 
 	// See https://dev.mysql.com/doc/refman/8.0/en/index-hints.html for more information on index hints.
 	IndexHint string // none or force or use