chore(git-node): improve instructions logs when manual amending is required (#560)

Author: juanarbol

lib/landing_session.js

@@ -436,6 +436,10 @@ export default class LandingSession extends Session {
 
       if (!forceLand) {
         cli.info('Please fix the commit message and try again.');
+        cli.log('Please manually ammend the commit message, by running\n' +
+          '`git commit --amend`\n' +
+          'Once commit message is fixed, finish the landing command running\n' +
+          '`git node land --continue`');
         process.exit(1);
       }
     }