Remove ignore D000 in validation code

This commit going to remove --ignore D000 which had raised
alot of issues, such as:
- "D000 Cannot analyze code. Pygments package not found."
- Cannot check LOG which have '_' symbol in code-base.

And they also fixed in https://review.openstack.org/#/c/568729/

Change-Id: Ic5258e0262c11b9f878d867a3354aa7d1f6e67b4

doc/source/admin/writing_pipeline_stages.rst

@@ -75,9 +75,7 @@ This is an example of small package with a stage that can process queue-related
 requests in Zaqar. The stage does not do anything useful, but is good as
 example.
 
-File tree structure of the package:
+File tree structure of the package::
-
-.. code-block:: none
 
    .
    ├── setup.py

test-requirements.txt

@@ -18,6 +18,7 @@ PyMySQL>=0.7.6 # MIT License
 coverage!=4.4,>=4.0 # Apache-2.0
 ddt>=1.0.1 # MIT
 doc8>=0.6.0 # Apache-2.0
+Pygments>=2.2.0 # BSD license
 fixtures>=3.0.0 # Apache-2.0/BSD
 
 testscenarios>=0.4 # Apache-2.0/BSD

tox.ini

@@ -46,6 +46,7 @@ commands = {posargs}
 [testenv:docs]
 deps =
   -r{toxinidir}/doc/requirements.txt
+  -r{toxinidir}/test-requirements.txt
 
 commands =
   doc8 doc/source
@@ -83,10 +84,6 @@ extensions = .rst, .yaml
 # Maximal line length should be 80 but we have some overlong lines.
 # Let's not get far more in.
 max-line-length = 80
-# Disable some doc8 checks:
-# D000: Check RST validity
-# - cannot handle "none" for code-block directive
-ignore = D000
 
 [hacking]
 local-check-factory = zaqar.hacking.checks.factory