Update minimum requirements for linux/ppc64 target

Updates golang/go#79898.

Change-Id: I1b726590ad06e24c3406c0f762b22f3cf1ab2179
Reviewed-on: https://go-review.googlesource.com/c/wiki/+/789180
Commit-Queue: Paul Murphy <paumurph@redhat.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

MinimumRequirements.md

diff --git a/MinimumRequirements.md b/MinimumRequirements.md
index 3d4af1e..3ab8ed5 100644
--- a/MinimumRequirements.md
+++ b/MinimumRequirements.md
@@ -128,9 +128,16 @@
 
 ### ppc64 (big endian)
 
-POWER5 and above.
+POWER8 and above.
+
+Prior to Go 1.9, POWER5 and newer processors were supported.
+
 Starting with Go 1.9, only POWER8 and above are supported.
 
+Starting with Go 1.27, the linux target ABI has changed from ELFv1 to ELFv2. This change requires a kernel which supports loading ELFv2 binaries.
+
+Starting with Go 1.27, the linux target supports external linking, cgo, and PIE buildmodes. These features require an ELFv2 userspace.
+
 ### ppc64le (little endian)
 
 POWER8 and above.