Readme - add brute-force protection examples links

[animir]

Passport Local Strategy is one of the most used for local authentication. It would be good, if it has this note about Brute-Force protection necessity to make the web safer place.

Checklist

• [x] I have read the CONTRIBUTING guidelines.
• [ ] I have added test cases which verify the correct operation of this feature or patch.
• [ ] I have added documentation pertaining to this feature or patch.
• [ ] The automated test suite ($ make test) executes successfully.
• [ ] The automated code linting ($ make lint) executes successfully.

[coveralls]

Coverage remained the same at 97.619% when pulling 6021a6cf51500c72fcd61b64a2a8403b3baceb39 on animir:patch-1 into 2bf3939ca369e08a47a28585c2ccfb3cecffeb9c on jaredhanson:master.