doc/go1.22: remove empty cgo section

doc/go1.22: remove empty cgo section

The only issue in this section, #56378, does not need a release note
for Go 1.22 because its feature was disabled for this release.

For #61422.
Updates #56378.

Change-Id: Ia4e090994cd9ac04e855f8b3a2c6ca0cde4485d2
Reviewed-on: https://go-review.googlesource.com/c/go/+/548876
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>