doc: improve document structure (fixes #1611)

Co-authored-by: Terri Oda <terri@toybox.ca>

CONTRIBUTING.md

@@ -11,7 +11,7 @@ If you've already contributed to other open source projects, contributing to the
   - [Setting up a virtualenv](#setting-up-a-virtualenv)
   - [Installing dependencies](#installing-dependencies)
   - [Running your local copy of CVE Binary Tool](#running-your-local-copy-of-cve-binary-tool)
-    - [Help, my checkers aren't loading](#help-my-checkers-arent-loading)
+  - [Help, my checkers aren't loading](#help-my-checkers-arent-loading)
   - [Running tests](#running-tests)
   - [Running linters](#running-linters)
     - [Using pre-commit to run linters automatically](#using-pre-commit-to-run-linters-automatically)
@@ -133,7 +133,7 @@ python3 -m pip install --user -e .
 
 Then you can type `cve-bin-tool` on the command line and it will do the right thing.  This includes some special code intended to deal with adding new checkers to the list on the fly so things should work seamlessly for you while you're building new contributions.
 
-### Help, my checkers aren't loading
+## Help, my checkers aren't loading
 
 CVE Binary Tool uses the installed egg file to figure out which checkers are installed. If you run it directly without installing it (e.g. you try to use `python -m cve_bin_tool.cli`), it will usually work fine but you may occasionally find that checkers aren't loading properly.  Typically this happens with new checkers you are adding, but sometimes if you `git pull` it will cause a similar effect.  If you get into this state, you can fix it by running the following command from the main cve-bin-tool directory: