Update pushdata-opcodes.mdx

Comment on the 520 byte limit making OP_PUSHDATA4 unusable

Author: deadmanoz

decoding/pushdata-opcodes.mdx

@@ -23,8 +23,8 @@ In bitcoin's scripting language, several opcodes are used to push data onto the
 4. **OP_1NEGATE**: Pushes the number -1 onto the stack.
 
 <ExpandableAlert title="Maximum Data Size" type="warning" expandable={false}>
-    The maximum amount of data that can be pushed in a single operation is **520
-    bytes**.
+    Due to practical limitations and security considerations, the maximum amount of data that can be pushed in a single operation is **520
+    bytes**. As such, the **OP_PUSHDATA4** opcode is never used in practice (it allows for pushing 65536-4294967295 bytes). 
 </ExpandableAlert>
 
 <ExpandableAlert