[css-mixins-1] Descrip -> Descriptor

css-mixins-1/Overview.bs

@@ -266,7 +266,7 @@ Additionally, it accepts the following descriptors:
 Unknown descriptors are invalid and ignored,
 but do not make the ''@function'' rule itself invalid.
 
-The '@function/result' Descrip {#the-result-descriptor}
+The '@function/result' Descriptor {#the-result-descriptor}
 ----------------------------------------------------------
 
 <pre class='descdef'>