ST1021: handle type names that are also articles

Closes gh-1187

Author: dominikh

stylecheck/lint.go

@@ -875,6 +875,11 @@ func CheckExportedTypeDocs(pass *analysis.Pass) (interface{}, error) {
 				}
 			}
 
+			// Check comment before we strip articles in case the type's name is an article.
+			if strings.HasPrefix(text, node.Name.Name+" ") {
+				return false
+			}
+
 			s := text
 			articles := [...]string{"A", "An", "The"}
 			for _, a := range articles {

stylecheck/testdata/src/CheckExportedTypeDocs/CheckExportedTypeDocs.go

@@ -55,3 +55,6 @@ type T13 struct{}
 //some:directive //@ diag(`comment on exported type`)
 // Whatever
 type T14 struct{}
+
+// A does stuff.
+type A struct{}