Update doc links to GitHub issues
Fix errors, warnings generated when Sphinx renders docs
Merge pull request #1355 from eeshangarg/bug-1354-fix-sphinx-errors-and-warnings

Fix errors, warnings generated when Sphinx renders docs
Fix the link to the training missions on the homepage
Merge pull request #1358 from eeshangarg/bug-1357-fix-missions-link-on-homepage

Fix the link to the training missions on the homepage
Merge pull request #1353 from willingc/docs-issue-tracker

Update doc links to GitHub issues (Issue #1350)