* Remove BertGenerationTokenizer from objects to ignore
The file BertGenerationTokenizer is removed from
objects to ignore as a first step to fix docstring.
* Docstrings fix for BertGenerationTokenizer
Docstring fix is generated for BertGenerationTokenizer
by using check_docstrings.py.
* Fix docstring for BertGenerationTokenizer
Added sep_token type and docstring in BertGenerationTokenizer.