Cleanup

- Use doc8 to check rst files
- Add spellcheck and VOLTHA-specific dictionary, fix spelling
- Other formatting and content fixes

Change-Id: I1eea3ab6eba4ec34af0788a681f1e8cd258ea988
diff --git a/conf.py b/conf.py
index ce7ea51..8f6ce2d 100644
--- a/conf.py
+++ b/conf.py
@@ -60,6 +60,7 @@
     'sphinxcontrib.packetdiag',
     'sphinxcontrib.rackdiag',
     'sphinxcontrib.seqdiag',
+    'sphinxcontrib.spelling',
 #    'sphinxcontrib.golangdomain',
 #    'autoapi.extension',
 ]
@@ -76,6 +77,9 @@
 #       'voltha-go/rw_core/utils',
 #   ]
 
+# Text files with lists of words that shouldn't fail the spellchecker:
+spelling_word_list_filename=['dict.txt', ]
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']