Add AIX triple to Cargo.toml for doc.

Xing Xue · tgross35 · commit df6346d95684 · 2025-06-03T20:31:07.000Z
(backport <#4475>) (cherry picked from commit 187707b)
diff --git a/Cargo.toml b/Cargo.toml
@@ -73,6 +73,7 @@ targets = [
     "powerpc-unknown-netbsd",
     "powerpc-wrs-vxworks",
     "powerpc-wrs-vxworks-spe",
+    "powerpc64-ibm-aix",
     "powerpc64-unknown-freebsd",
     "powerpc64-unknown-linux-gnu",
     "powerpc64-wrs-vxworks",
