Fix https://github.com/Microsoft/TypeScript/issues/12316: Add method to known tag names

src/services/jsDoc.ts

@@ -23,6 +23,7 @@ namespace ts.JsDoc {
         "lends",
         "link",
         "memberOf",
+        "method",
         "name",
         "namespace",
         "param",

tests/cases/fourslash/completionInJsDoc.ts

@@ -30,6 +30,7 @@ goTo.marker('1');
 verify.completionListContains("constructor");
 verify.completionListContains("param");
 verify.completionListContains("type");
+verify.completionListContains("method");
 
 goTo.marker('2');
 verify.completionListContains("constructor");