add api-extractor to rc types

Author: Feiyang1

packages-exp/remote-config-types-exp/api-extractor.json

@@ -0,0 +1,5 @@
+{
+    "extends": "../../config/api-extractor.json",
+    // Point it to your entry point d.ts file. 
+    "mainEntryPointFilePath": "<projectFolder>/index.d.ts"
+}

packages-exp/remote-config-types-exp/package.json

@@ -6,7 +6,11 @@
   "license": "Apache-2.0",
   "scripts": {
     "test": "tsc",
-    "test:ci": "node ../../scripts/run_tests_in_ci.js"
+    "test:ci": "node ../../scripts/run_tests_in_ci.js",
+    "api-report": "api-extractor run --local --verbose",
+    "predoc": "node ../../scripts/exp/remove-exp.js temp",
+    "doc": "api-documenter markdown --input temp --output docs",
+    "build:doc": "yarn api-report && yarn doc"
   },
   "files": [
     "index.d.ts"