Minimum Word Length

**Is your feature request related to a problem? Please describe.**
The plugin ends suggesting a large number of inappropriate links because it tries to link single/double letters and numbers. 

**Describe the solution you'd like**
Allow a configurable minimum word length for the plugin to look for links for. ie, length=4 would look for 'Rust' but not '10', 'SR4', 'Jan', etc.

Thanks!