[core] Fix docs:api cleaning the wrong directory (#20164)

Author: ro7584

package.json

@@ -6,7 +6,7 @@
     "deduplicate": "node scripts/deduplicate.js",
     "argos": "argos upload test/regressions/screenshots/chrome --token $ARGOS_TOKEN",
     "build:codesandbox": "lerna run --parallel --scope \"@material-ui/*\" build",
-    "docs:api": "rimraf ./docs/pages/api && cross-env BABEL_ENV=test __NEXT_EXPORT_TRAILING_SLASH=true babel-node ./docs/scripts/buildApi.js ./packages/material-ui/src ./docs/pages/api-docs && cross-env BABEL_ENV=test __NEXT_EXPORT_TRAILING_SLASH=true babel-node ./docs/scripts/buildApi.js ./packages/material-ui-lab/src ./docs/pages/api-docs",
+    "docs:api": "rimraf ./docs/pages/api-docs && cross-env BABEL_ENV=test __NEXT_EXPORT_TRAILING_SLASH=true babel-node ./docs/scripts/buildApi.js ./packages/material-ui/src ./docs/pages/api-docs && cross-env BABEL_ENV=test __NEXT_EXPORT_TRAILING_SLASH=true babel-node ./docs/scripts/buildApi.js ./packages/material-ui-lab/src ./docs/pages/api-docs",
     "docs:build": "yarn workspace docs build",
     "docs:build-sw": "yarn workspace docs build-sw",
     "docs:build-color-preview": "babel-node scripts/buildColorTypes",