Docs: clarify behavior of range checks

The current wording (about the sets of values being "the same") is not
accurate.

Author: nickrolfe

docs/codeql/ql-language-reference/formulas.rst

@@ -133,13 +133,11 @@ A range check is a formula that looks like:
 
     <expression> in <range>
 
-You can use a range check formula to check whether a numeric expression is in a given 
+It holds if there is at least one value in ``<expression>`` that is also in the given
 :ref:`range <ranges>`. For example, ``x in [2.1 .. 10.5]`` holds if the variable ``x`` is 
 between the values ``2.1`` and ``10.5`` (including ``2.1`` and ``10.5`` themselves).
 
 Note that ``<expression> in <range>`` is equivalent to ``<expression> = <range>``. 
-Both formulas check whether the set of values denoted by ``<expression>`` is the same as the
-set of values denoted by ``<range>``.
 
 .. _calls: