[mode/meta] Add cbl extension for Cobol

Closes codemirror#6762

Author: marijnh

mode/meta.js

@@ -19,7 +19,7 @@
     {name: "Brainfuck", mime: "text/x-brainfuck", mode: "brainfuck", ext: ["b", "bf"]},
     {name: "C", mime: "text/x-csrc", mode: "clike", ext: ["c", "h", "ino"]},
     {name: "C++", mime: "text/x-c++src", mode: "clike", ext: ["cpp", "c++", "cc", "cxx", "hpp", "h++", "hh", "hxx"], alias: ["cpp"]},
-    {name: "Cobol", mime: "text/x-cobol", mode: "cobol", ext: ["cob", "cpy"]},
+    {name: "Cobol", mime: "text/x-cobol", mode: "cobol", ext: ["cob", "cpy", "cbl"]},
     {name: "C#", mime: "text/x-csharp", mode: "clike", ext: ["cs"], alias: ["csharp", "cs"]},
     {name: "Clojure", mime: "text/x-clojure", mode: "clojure", ext: ["clj", "cljc", "cljx"]},
     {name: "ClojureScript", mime: "text/x-clojurescript", mode: "clojure", ext: ["cljs"]},