@?: Add note on application of multiple @-modifiers

[kazarmy]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

This pr adds a note to @? regarding application of multiple @-modifiers. I think it's more natural (and preferable) for the application to be left-to-right rather than right-to-left, but that's a story for another pr.

Test plan

The changes make sense.

Closing issues

...

[XVilka]

Do we have a test that actually checks @ behaves this way?

[kazarmy]

Do we have a test that actually checks @ behaves this way?

rizin/test/db/cmd/cmd_px

Lines 394 to 396 in 21d308b

	NAME=pxi
	FILE=malloc://0xd+0x30
	CMDS=pxi @!0x10+0x30 @x:f30f1efa554889e5ebfe

[XVilka]

Open an issue please about the LTR/RTL behavior please too

[kazarmy]

Ok #4816