chore(docs): prune docs snapshots that are never built, and bound the directory (#13608)

Author: AztecBot

docs/README.md

@@ -101,14 +101,21 @@ yarn cut_version <VERSION>
 
 For example: `yarn cut_version v1.0.0-beta.20`
 
-This script does three things:
+This script does four things:
 
 1. Removes the new version from `versions.json` (since `yarn version::stables` will have added it
    from the GitHub release, but the versioned docs snapshot doesn't exist yet).
 2. Builds the docs (running preprocessing to resolve `#include_code` directives and generate the
    Nargo CLI reference).
 3. Runs `yarn docusaurus docs:version <VERSION>` to snapshot the current docs into
    `versioned_docs/version-<VERSION>/` and create a matching sidebar in `versioned_sidebars/`.
+4. Deletes any snapshot older than the newest `VERSIONS_TO_KEEP` (see `scripts/cut_version.sh`),
+   keeping `versioned_docs/` bounded. Only the versions listed in `versions.json` are ever built
+   and served — `scripts/setStable.ts` caps that list at `NUMBER_OF_VERSIONS_TO_SHOW` — so older
+   snapshots are dead weight in the repository. `VERSIONS_TO_KEEP` is deliberately larger than
+   `NUMBER_OF_VERSIONS_TO_SHOW`, so raising the number of served versions does not immediately
+   require re-cutting a snapshot that has already been deleted. Docs for deleted versions remain
+   available at their published URLs and in git history.
 
 After this, the new version will appear in the version dropdown on the site.
 

docs/scripts/cut_version.sh

@@ -14,3 +14,15 @@ yarn build
 
 # Finally cut the actual new docs version.
 yarn docusaurus docs:version $VERSION
+
+# Docusaurus only builds the versions listed in `versions.json`, which `scripts/setStable.ts`
+# caps at NUMBER_OF_VERSIONS_TO_SHOW. Snapshots older than that are never built, routed or
+# linked, so drop them here instead of carrying one more directory per release forever.
+# Keep more than are served so that raising NUMBER_OF_VERSIONS_TO_SHOW does not immediately
+# require re-cutting docs that were already deleted.
+VERSIONS_TO_KEEP=8
+
+ls -1 versioned_docs | sort -rV | tail -n +$((VERSIONS_TO_KEEP + 1)) | while read -r dir; do
+  echo "Pruning docs snapshot that is no longer served: $dir"
+  rm -rf "versioned_docs/$dir" "versioned_sidebars/${dir}-sidebars.json"
+done