Update docs/src/concepts.md

Co-authored-by: Kabilar Gunalan <kabilar@datajoint.com>

Author: JaerongA

docs/src/concepts.md

@@ -157,7 +157,7 @@ Tables for storing probe or unit-level visualization results.
 | ProbeLevelReport | A table to store drift map figures generated from each recording probe. |
 | UnitLevelReport | A table to store figures (waveforms, autocorrelogram, peak waveform + neighbors) generated for each unit. |
 | QualityMetricCutoffs | A table to store cut-off values for cluster quality metrics. |
-| QualityMetricSet | A table to store a set of quality metric values for clusters and its cut-offs. |
+| QualityMetricSet | A manual table to match a set of cluster quality metric values with desired cut-offs. |
 | QualityMetricReport | A table to store quality metric figures. |
 
 ## Element Development