Update powerpc64-wrs-vxworks platform support docs

Author: B I Mohammed Abbas

src/doc/rustc/src/platform-support.md

@@ -339,7 +339,7 @@ target | std | host | notes
 `powerpc64le-unknown-freebsd` |   |   | PPC64LE FreeBSD
 `powerpc-unknown-freebsd` |   |   | PowerPC FreeBSD
 `powerpc64-unknown-linux-musl` | ? |  | 64-bit PowerPC Linux with musl 1.2.3
-`powerpc64-wrs-vxworks` | ? |  |
+[`powerpc64-wrs-vxworks`](platform-support/vxworks.md) | ? |  |
 `powerpc64le-unknown-linux-musl` | ? |  | 64-bit PowerPC Linux with musl 1.2.3, Little Endian
 [`powerpc64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | OpenBSD/powerpc64
 [`powerpc64-ibm-aix`](platform-support/aix.md) | ? |  | 64-bit AIX (7.2 and newer)

src/doc/rustc/src/platform-support/vxworks.md

@@ -12,6 +12,7 @@ Target triplets available:
 - `i686-wrs-vxworks`
 - `armv7-wrs-vxworks-eabihf`
 - `powerpc-wrs-vxworks`
+- `powerpc64-wrs-vxworks`
 - `powerpc-wrs-vxworks-spe`
 
 ## Target maintainers
@@ -36,6 +37,7 @@ target = [
     "i686-wrs-vxworks",
     "armv7-wrs-vxworks-eabihf",
     "powerpc-wrs-vxworks",
+    "powerpc64-wrs-vxworks",
     "powerpc-wrs-vxworks-spe",
 ]
 ```