add bazel command to generate API docs

[facaiy]

Fix #46
Related PRs: #140, #195, #196

bazel build tools/docs:build_docs
bazel-bin/tools/docs/build_docs --git_branch=master --output_dir=docs/api_docs/python/

I push the documnets generated to my repository, and everyone can preview it at https://github.com/facaiy/addons/blob/tf_addons_doc_preview/docs/api_docs/python/tfa.md

[facaiy]

It's still not perfect, I think there are three problems, take tf_addons.activations as an example:

1. we need to filter out those members of __futures__ module: absolute_import, division, print_function.
2. tensorflow_docs cannot recognize tf.function function: sparsemax.
3. we also need to bypass private member, for example: __version__ in https://github.com/facaiy/addons/blob/tf_addons_doc_preview/docs/api_docs/python/tf_addons.md

@lamberta @MarkDaoust Hi, can we find a better way to solve those problems?

[facaiy]

Gently ping @lamberta @MarkDaoust

[facaiy]

@seanpmorgan Sean, do we need to generate api documents for 0.3 release?

[lamberta]

@yashk2810 recently added tensorflow/docs@5afa339 that should filter out a few more.
Yash, can you look into the other issues in this PR? Thanks

[facaiy]

Thank you, Billy, I'll take a try today

[MarkDaoust]

So for those three questions:

1. Should be fixed.
2. The simplest fix is to patch in tensorflow's version of the tf_inspect module, since tf.function is following the tf_decoratorprotocol.

from tensorflow_docs.api_generator import parser
from tensorflow.python.util import tf_inspect

 # Use tensorflow's `tf_inspect`, which is aware of `tf_decorator`.
parser.tf_inspect = tf_inspect

3. It's not clear that blocking all __dunder__ symbols is the right answer. The simplest way to block a single symbol is to just delete it from the module before running the doc generator del tf_addons.__version__. Passing private_map={'tf_addons',['__version__']} to the constructor would also work. If you need a more powerful filter you can add a callback to the list "callbacks=[public_api.local_definitions_filter]".

[facaiy]

@MarkDaoust Awesome, it works. Thanks for your help, Mark!

[facaiy]

@seanpmorgan @tensorflow/sig-addons-maintainers Hi, we can preview the document at https://github.com/facaiy/addons/blob/tf_addons_doc_preview/docs/api_docs/python/tfa.md

Could you take a look? And I think we can use it to generate API doc for 0.3 release.

[seanpmorgan]

@facaiy This looks great, thanks for getting this done it is much needed. My only question would be how do we intend to upload the docs on the release branch given the .gitignore? We could modify the .gitignore on the release branch?

Other than that LGTM for merging

[facaiy]

My only question would be how do we intend to upload the docs on the release branch given the .gitignore?

Good question! We have to use git add -f doc to do it explicitly on the release branch. I'm worried that someone might add doc into master branch inadvertently, that's why we put /doc/ in the gitignore file.

[seanpmorgan]

Thanks!