message: update `docusaurus` to v2.1
diff: "write-heading-ids": "docusaurus write-heading-ids"
  },
  "dependencies": {
  - "@docusaurus/core": "2.0.1",
  - "@docusaurus/module-type-aliases": "2.0.1",
  - "@docusaurus/preset-classic": "2.0.1",
  - "@docusaurus/theme-search-algolia": "2.0.1",
  + "@docusaurus/core": "2.1.0",
  + "@docusaurus/module-type-aliases": "2.1.0",
  + "@docusaurus/preset-classic": "2.1.0",
  + "@docusaurus/theme-search-algolia": "2.1.0",
  "@tsconfig/docusaurus": "~1.0.6",
  "@types/react": "~17.0.39",
  "cross-env": "~7.0.3",
  