Update performance_faq.md

site/en/faq/performance_faq.md

@@ -22,7 +22,7 @@ The following charts are results from a test running on the sift50m dataset and
 
 #### Why do queries sometimes take longer on smaller datasets?
 
-Query operations are conducted on segments. indexes reduce the amount of time it takes to query a segment. If a segment has not been indexed, Milvus resorts to brute-force search on the raw data—drastically increasing query time.
+Query operations are conducted on segments. Indexes reduce the amount of time it takes to query a segment. If a segment has not been indexed, Milvus resorts to brute-force search on the raw data—drastically increasing query time.
 
 Therefore, it usually takes longer to query on a small dataset (collection) because it has not built index. This is because the sizes of its segments have not reached the index-building threshold set by `rootCoord.minSegmentSizeToEnableindex`. Call `create_index()` to force Milvus to index segments that have reached the threshold but not yet been automatically indexed, significantly improving query performance.