Promote FP8 ACLE status from Alpha to Beta (#388)

The support for modal 8-bit floating point intrinsics, FP8 ACLE, has
being implemented in upstream by Clang/LLVM and GCC, so I think they're
ready to be treated as Beta.

Author: CarolineConcatto

main/acle.md

@@ -445,6 +445,8 @@ Armv8.4-A [[ARMARMv84]](#ARMARMv84). Support is added for the Dot Product intrin
 * Added `svdot[_n_f16_mf8]_fpm` and `svdot[_n_f32_mf8]_fpm`.
 * Added Guarded Control Stack (GCS) at
   [**Beta**](#current-status-and-anticipated-changes) quality level.
+* Upgrade to [**Beta**] (#current-status-and-anticipated-changes)
+  support for modal 8-bit floating point intrinsics.
 
 #### Changes for next release
 
@@ -5920,7 +5922,7 @@ each architecture includes its predecessor instruction set.
 # About FP8 intrinsics
 
 The specification for FP8 intrinsics is in
-[**Alpha** state](#current-status-and-anticipated-changes).
+[**Beta** state](#current-status-and-anticipated-changes).
 
 Each 8-bit floating point intrinsic call has a parameter to define the format
 and scale of the operands, and the overflow behavior, as applicable to each