doc8 is a linter for documents and used in openstack-manuals.
It is better to enforce document linters for simple checking.
This change is to add doc8 in tox file and fix line too long
in some files.
The current rules are as bellow:
- invalid rst format - D000
- lines should not be longer than 79 characters - D001
- RST exception: line with no whitespace except in the beginning
- RST exception: lines with http or https urls
- RST exception: literal blocks
- RST exception: rst target directives
- no trailing whitespace - D002
- no tabulation for indentation - D003
- no carriage returns (use unix newlines) - D004
- no newline at end of file - D005
Change-Id: I5b409fbfd95e05921310c6ecf4afea0220fb0bf0
f18dc29eb0