build(aio): move zip and live-example generation to yarn predocs ta…

…sk (#21970)

This will prevent the confusing errors for first time users who
try to generate the docs with `yarn docs` and are told there are
dangling links.

Closes #21944

PR Close #21970

aio/package.json

@@ -23,7 +23,7 @@
     "preinstall": "node ../tools/yarn/check-yarn.js",
     "presetup": "yarn install --frozen-lockfile && yarn ~~check-env && yarn boilerplate:remove",
     "setup": "yarn aio-use-npm && yarn example-use-npm",
-    "postsetup": "yarn boilerplate:add && yarn build-ie-polyfills && yarn generate-stackblitz && yarn generate-zips && yarn docs",
+    "postsetup": "yarn boilerplate:add && yarn build-ie-polyfills && yarn docs",
     "presetup-local": "yarn presetup",
     "setup-local": "yarn aio-use-local && yarn example-use-local",
     "postsetup-local": "yarn postsetup",
@@ -39,6 +39,7 @@
     "check-env": "yarn ~~check-env",
     "postcheck-env": "yarn aio-check-local",
     "payload-size": "scripts/payload.sh",
+    "predocs": "yarn generate-stackblitz && yarn generate-zips",
     "docs": "dgeni ./tools/transforms/angular.io-package",
     "docs-watch": "node tools/transforms/authors-package/watchr.js",
     "docs-lint": "eslint --ignore-path=\"tools/transforms/.eslintignore\" tools/transforms",