Add code block in README for gemspec

Author: dhivyadandapani

README.rdoc

@@ -49,7 +49,7 @@ useful. If there is another library which handles it, we list it here.
 
 To install all the dependencies for local development:
 
-* gem build net-ldap.gemspec
+  gem build net-ldap.gemspec
 
 This task will run the test suite and the
 {RuboCop}[https://github.com/bbatsov/rubocop] static code analyzer.