Update developer page with tox method for building sphinx docs

* changes are in 02_building_complianceascode.md

Signed-off-by: Stephen L Arnold <[email protected]>

docs/manual/developer/02_building_complianceascode.md

@@ -159,6 +159,26 @@ apt-get install ninja-build
 
 ### Sphinx packages (Developer Documentation)
 
+Building docs can be done via tox file or manually.  Note that tox creates a
+virtual environment to handle all dependencies defined in the docs requirements
+file.
+
+#### Using the tox file
+
+```bash
+# Fedora/RHEL
+yum install tox
+
+# Ubuntu/Debian
+apt-get install tox
+```
+
+```bash
+tox -e docs
+```
+
+#### Manual method
+
 Install Sphinx packages if you want to generate HTML Documentation, from source directory run:
 
 ```bash
@@ -173,6 +193,10 @@ apt-get install python3-sphinx
 pip install -r docs/requirements.txt
 ```
 
+```bash
+make -C docs html
+```
+
 ### Pandas (SRG Export HTML)
 
 Install `pandas` if you want to run `utils/create_srg_export.py`: