Update stripPrefix documentation to talk about no op case

Update StringLike Documentation to indicate what happens when you remove a prefix from a string, and the string doesn't have that prefix.
Since you're squashing anyway, this is a typo: s/is of/of/.  Also I guess s/caller/string/, since I see now that all the other docs say that, although StringLike doesn't have to wrap a String.

Also, my suggestion was to add the code: 
```
else if (toString.charAt(0).isUpper) toString
```
though that's just a boy scout suggestion.