[FMV] Upgrade Function Multi Versioning to Release support level. (#425)

Support level is now production ready, therefore remove the Beta annotation.

Author: labrinea

main/acle.md

@@ -472,6 +472,7 @@ Armv8.4-A [[ARMARMv84]](#ARMARMv84). Support is added for the Dot Product intrin
 * Added support for modal 8-bit floating point matrix multiply-accumulate widening intrinsics.
 * Added support for 16-bit floating point matrix multiply-accumulate widening intrinsics.
 * Added restrictions of Function Multi Versioning's use with other extensions.
+* Upgrade Function Multi Versioning to Release support level.
 
 ### References
 
@@ -2776,10 +2777,6 @@ This attribute does not apply to AArch64.
 
 ## Function Multi Versioning
 
-The specification for Function Multi Versioning is in [**Beta**
-state](#current-status-and-anticipated-changes) and might change or be
-extended in the future.
-
 Function Multi Versioning provides a convenient way to select the most
 appropriate version of a function at runtime. All versions of the
 function may be in the final binary. The compiler generates all