Fix v2 tag format: modules/<name>/<version>, not modules/<name>/v2/<version>

The submodule go.mod files live at modules/<name>/ (the /v2 is the SIV in the
module path, not a directory), so Go resolves each module's version tag at
<subdir>/<version> = modules/<name>/<version> (e.g. modules/aws/v2.0.0-beta.1).
The workflow and runbook incorrectly put the /v2 in the tag itself
(modules/aws/v2/v2.0.0-beta.1), which the module proxy cannot associate with the
module path, so no consumer could resolve the tags.

Caught by an end-to-end consumer test against the pushed beta tags: core (no
cross-module deps) resolved, every other module failed with
'ssh/v2@v2.0.0-00010101...: unknown revision' because the placeholder-free tag
was published under the wrong name. The proxy-verify URL is unchanged (it
correctly uses the full module path, which does include /v2).

Author: james00012

.github/workflows/create-release.yml

@@ -116,7 +116,7 @@ jobs:
         run: |
           set -e
           for path in $MODULE_PATHS; do
-            tag="${path}/v2/${VERSION}"
+            tag="${path}/${VERSION}"
             if [ "$DRY_RUN" = "true" ]; then
               echo "DRY-RUN would tag ${PINNED_SHA:0:12}: $tag"
             else

docs/v2-release-runbook.md

@@ -68,11 +68,14 @@ build is validated continuously without committing the pin or needing tags.
 
 ## Tag push order
 
-All tags point at the same release commit. Each tag name puts the `/v2` SIV in the
-tag itself: `modules/<name>/v2/<version>` (NOT `modules/<name>/<version>`, which
-the proxy cannot associate with the `/v2` module path). Push in dependency order:
-
-1. `modules/core/v2/v2.0.0-beta.1`
+All tags point at the same release commit. The tag name is the module's
+on-disk subdirectory (which does NOT include the `/v2`, since `/v2` is only the
+SIV in the module path, not a directory) followed by the version:
+`modules/<name>/<version>`, e.g. `modules/aws/v2.0.0-beta.1`. Do NOT put the
+`/v2` in the tag (`modules/<name>/v2/<version>`), Go looks for the tag at
+`<subdir>/<version>` and will not find it. Push in dependency order:
+
+1. `modules/core/v2.0.0-beta.1`
 2. helpers: `ssh`, `httphelper`, `dnshelper`
 3. tooling: `docker`, `packer`, `database`, `opa`
 4. platforms: `aws`, `azure`, `gcp`, then `k8s`, `helm`