[ios, macos] Note that no modifier operators are supported

There’s also an “l” operator for locale sensitivity.

platform/darwin/src/MGLVectorStyleLayer.h

@@ -62,8 +62,9 @@ NS_ASSUME_NONNULL_BEGIN
  To test whether a feature has or lacks a specific attribute, compare the attribute to `NULL` or `NIL`. Predicates created using the `+[NSPredicate predicateWithValue:]` method are also supported. String operators and custom operators are not supported.
  
  For details about the predicate format string syntax, consult the “Predicate
- Format String Syntax” chapter of the “Predicate Programming Guide” in Apple
- developer documentation.
+ Format String Syntax” chapter of the
+ “<a href="https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/Predicates/">Predicate Programming Guide</a>”
+ in Apple developer documentation.
  
  The predicate's left-hand expression must be a string that identifies a feature
  attribute or, alternatively, one of the following special attributes:
@@ -119,9 +120,10 @@ NS_ASSUME_NONNULL_BEGIN
  
  Automatic type casting is not performed. Therefore, a feature only matches this
  predicate if its value for the attribute in question is of the same type as the
- value specified in the predicate. Also, operator modifiers `c`, `d`, and the
- combined `cd` for case and diacritic insensitivity are unsupported for 
- comparison and aggregate operators that are used in the predicate.
+ value specified in the predicate. Also, operator modifiers such as `c` (for
+ case insensitivity), `d` (for diacritic insensitivity), and `l` (for locale
+ sensitivity) are unsupported for comparison and aggregate operators that are
+ used in the predicate.
  
  It is possible to create expressions that contain special characters in the 
  predicate format syntax. This includes the `$` in the `$id` and `$type` special