Update README.md

This pull request only adds a '=' in comment lines so comments for true and false compares match. No other files have been modified.

BEFORE
```
bcrypt.compare("B4c0/\/", hash, function(err, res) {
    // res == true
});
bcrypt.compare("not_bacon", hash, function(err, res) {
    // res = false
});
```
AFTER
```
bcrypt.compare("B4c0/\/", hash, function(err, res) {
    // res == true
});
bcrypt.compare("not_bacon", hash, function(err, res) {
    // res == false
});
```