fix: add static discovery docs (#1216)
Fixes #1214
The [MANIFEST.in](https://packaging.python.org/guides/using-manifest-in/) controls which files are included in the published package.
You can verify that this fixes the problem (missing discovery docs leading to failing `discovery.build()` calls) by building the package and installing the library from the tarfile.
- `python3 -m venv env`
- `source env/bin/activate`
- `python3 -m setup.py sdist`
- `python3 -m pip install dist/google-api-python-client-2.0.0.tar.gz`
```
(env) busunkim@busunkim:~/github/google-api-python-client$ python3
Python 3.6.9 (default, Feb 24 2020, 21:10:07)
[GCC 9.2.1 20190909] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import googleapiclient
>>> from googleapiclient import discovery
>>> client = discovery.build("cloudprofiler", "v2")
>>>
```diff --git a/MANIFEST.in b/MANIFEST.in
index dc06524..5b18ef6 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,5 @@
recursive-include apiclient *.json *.py
+recursive-include googleapiclient *.json *.py
include CHANGELOG
include LICENSE
include README