Update README.md for #1068

Author: bjorn3

Readme.md

@@ -75,7 +75,6 @@ function jit_calc() {
 ## Not yet supported
 
 * Good non-rust abi support ([several problems](https://github.com/bjorn3/rustc_codegen_cranelift/issues/10))
-    * Proc macros
 * Inline assembly ([no cranelift support](https://github.com/bytecodealliance/wasmtime/issues/1041)
     * On Linux there is support for invoking an external assembler for `global_asm!` and `asm!`.
       `llvm_asm!` will remain unimplemented forever. `asm!` doesn't yet support reg classes. You