fix: added docsearch dependency back

Author: NataliaTepluhina

src/.vuepress/theme/package.json

@@ -24,6 +24,7 @@
     "@vuepress/plugin-active-header-links": "^1.3.1",
     "@vuepress/plugin-nprogress": "^1.3.1",
     "@vuepress/plugin-search": "^1.3.1",
+    "docsearch.js": "^2.5.2",
     "lodash": "^4.17.15",
     "stylus": "^0.54.5",
     "stylus-loader": "^3.0.2",