docs: add kernel version-specific selector limits

Follow-up to PR #4549 documenting additional limits from issue #709.

Signed-off-by: Pavan More <[email protected]>

Author: puwun

docs/content/en/docs/concepts/tracing-policy/selectors.md

@@ -2056,6 +2056,15 @@ exist.
 For an unlimited number of values, consider using the `InMap` or `NotInMap`
 operators which store values in a BPF map.
 
+#### Kernel Version-Specific Limits
+
+Some limits vary based on the kernel version:
+
+- **Max file match values** (using `fd` or `file` arg): 8 on kernels ≥5.3, 2 on kernels <5.3
+- **String prefix max length**: 256 chars
+- **String postfix max length**: 128 chars
+- **matchBinaries values**: Unlimited (stored in BPF map)
+
 
 ## Return Actions filter