Complete README?

README.md

@@ -89,6 +89,20 @@ When we run `A` through the generated lexer, it will return that it's a `CAPITAL
 
 ### Regular expressions
 
+Most posix regular expression features have been implemented, with the exception of some notable features:
+
+* There is no way to match the beginning or ending of a line (`^` or `$`)
+* Repetition using `{` and `}` is (not yet) supported
+
+It should be noted that escape characters inside character classes don't exist, so a `-` that is part of the class should be specified as very first or very last element of the class (and cannot be used as endpoint of a range), and a `]` should be specified as first element. A `^` however should not be used as first element, unless it is meant as an inversion modifier for the character class.
+
+When needed (for example at the beginning of a rule, when whitespace is stripped by the reading of the input rules) a space can be specified as `\s` for convenience. Otherwise `[ ]`, a character class containing only a space can be used as well.
+
+### Using the lexer
+
+Of course, how you use the generated lexer highly depends on which backend you used to generate it. For the default c++ backend however, the easiest way of getting to know the lexer is probably having a look at the generated header file, usually named *<Lexername>.h*.
+In general, there should be some way the tokens are defined, and there should be some way to generate a list of tokens (or get each tokens separately).
+
 ## More examples
 More examples can be found in the *examples* subdirectory, go ahead an have a look at them.
 Feel free to play around and experiment with them.