Documentation for RNDR and RNDRRS

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15361)

CHANGES.md

@@ -24,6 +24,11 @@ OpenSSL 3.1
 
 ### Changes between 3.0 and 3.1 [xx XXX xxxx]
 
+ * RNDR and RNDRRS support in provider functions to provide
+   random number generation for Arm CPUs (aarch64).
+
+   *Orr Toledano*
+
  * s_client and s_server apps now explicitly say when the TLS version
    does not include the renegotiation mechanism. This avoids confusion
    between that scenario versus when the TLS version includes secure

INSTALL.md

@@ -446,7 +446,8 @@ This source is ignored by the FIPS provider.
 
 ### rdcpu
 
-Use the `RDSEED` or `RDRAND` command if provided by the CPU.
+Use the `RDSEED` or `RDRAND` command on x86 or `RNDRRS` command on aarch64
+if provided by the CPU.
 
 ### librandom