Help: Non-zero floating point numbers are true in if() expressions

Fixes: #22991

Help/command/if.rst

@@ -52,7 +52,8 @@ Basic Expressions
 
 ``if(<constant>)``
  True if the constant is ``1``, ``ON``, ``YES``, ``TRUE``, ``Y``,
- or a non-zero number.  False if the constant is ``0``, ``OFF``,
+ or a non-zero number (including floating point numbers).
+ False if the constant is ``0``, ``OFF``,
  ``NO``, ``FALSE``, ``N``, ``IGNORE``, ``NOTFOUND``, the empty string,
  or ends in the suffix ``-NOTFOUND``.  Named boolean constants are
  case-insensitive.  If the argument is not one of these specific