Update main README--move extra word out of link text.

Third to last paragraph of Overview section refers to cron.  The word "via", right before "cron" was included in the link to cron.  See image:

![screen shot 2014-09-18 at 9 32 20 pm](https://cloud.githubusercontent.com/assets/4251807/4330809/f1bfdd26-3fb6-11e4-9224-014ce9c9492f.png)