moved some TODOs into readme

org.springframework.expression/readme.txt

@@ -17,3 +17,10 @@ would have taken?  At the moment ternary expressions are just considered NOT wri
 Syntax
 
 - are distanceto or soundslike any use?
+- should the 'is' operator change to 'instanceof' ?
+- in this expression we hit the problem of not being able to write chars, since '' always means string:
+  evaluate("new java.lang.String('hello').charAt(2).equals('l'.charAt(0))", true, Boolean.class);
+  So 'l'.charAt(0) was required - wonder if we can build in a converter for a single length string to char?
+  Can't do that as equals take Object and so we don't know to do a cast in order to pass a char into equals
+  We certainly cannot do a cast (unless casts are added to the syntax).  See MethodInvocationTest.testStringClass()
+