docs: add missing doc

Author: ldez

.golangci.next.reference.yml

@@ -1840,6 +1840,8 @@ linters-settings:
       - unusedresult
       # Checks for unused writes.
       - unusedwrite
+      # Checks for misuses of sync.WaitGroup.
+      - waitgroup
 
     # Enable all analyzers.
     # Default: false

jsonschema/golangci.next.jsonschema.json

@@ -210,7 +210,8 @@
         "unreachable",
         "unsafeptr",
         "unusedresult",
-        "unusedwrite"
+        "unusedwrite",
+        "waitgroup"
       ]
     },
     "revive-rules": {