Clarify babel version error message

Author: pjcarly

ts/addon.ts

@@ -146,9 +146,9 @@ export default addon({
     let version = babel && babel.pkg.version;
 
     if (!babel || !(semver.gte(version!, '7.17.0') && semver.lt(version!, '8.0.0'))) {
-      let versionString = babel ? `version ${babel.pkg.version}` : `no instance of ember-cli-babel`;
+      let versionString = babel ? `version ${babel.pkg.version} installed` : `no instance of ember-cli-babel installed in your dependencies (check if it's in devDependencies instead?)`;
       this.ui.writeWarnLine(
-        `ember-cli-typescript requires ember-cli-babel ^7.17.0, but you have ${versionString} installed; ` +
+        `ember-cli-typescript requires ember-cli-babel ^7.17.0, but you have ${versionString}; ` +
           'your TypeScript files may not be transpiled correctly.'
       );
     }