Bump typedoc from 0.14.2 to 0.15.0 in /api

Bumps [typedoc](https://github.com/TypeStrong/TypeDoc) from 0.14.2 to 0.15.0.
- [Release notes](https://github.com/TypeStrong/TypeDoc/releases)
- [Commits](TypeStrong/typedoc@v0.14.2...v0.15.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

api/package.json

@@ -109,7 +109,7 @@
     "run-sequence": "2.2.1",
     "temp": "^0.9.0",
     "tslint": "5.18.0",
-    "typedoc": "^0.14.2",
+    "typedoc": "^0.15.0",
     "typescript": "^3.3.4000"
   },
   "engines": {