Hi,

As it stands, GCC doesn't document any public AArch64-specific operand
modifiers for use in inline asm.  This patch fixes that by documenting
an initial set of public AArch64-specific operand modifiers.

Tested with make html and checking the output looks OK in a browser.

OK for trunk?

Thanks,
Alex

gcc/ChangeLog:

	* doc/extend.texi: Document AArch64 Operand Modifiers.