Remove inaccurate claim about inline assembly

It's not like GCC's.

Fixes #20213

Author: steveklabnik

src/doc/book/inline-assembly.md

@@ -2,8 +2,7 @@
 
 For extremely low-level manipulations and performance reasons, one
 might wish to control the CPU directly. Rust supports using inline
-assembly to do this via the `asm!` macro. The syntax roughly matches
-that of GCC & Clang:
+assembly to do this via the `asm!` macro.
 
 ```ignore
 asm!(assembly template