📝 Document multistage-CI

Author: shnizzedy

docs/_sources/_static/flowcharts/CI-flow.svg

@@ -0,0 +1,8 @@
+Continuous Integration
+======================
+
+Our continous integration flow relies on GitHub Actions, GitHub Container Registry, CircleCI and Docker Hub. GitHub Actions builds staging images based on changes to Dockerfiles and pushes those images to GitHub Container Registry. On each push, once staging images are built or determined to be up to date, GitHub Actions installs C-PAC into a development image for each variant (standard, lite, fMRIPrep-LTS, and ABCD-HCP). CircleCI runs tests in both Docker and Singularity for each of these images and generates a coverage report if all tests pass. On release, CircleCI also pushes production images to Docker Hub.
+
+.. raw:: html
+
+    <div class="flowchart-container"><object data="../_static/flowcharts/CI-flow.svg" type="image/svg+xml"></object></div>

docs/_sources/developer/continuous_integration.rst

@@ -24,6 +24,7 @@ Contents:
    workflows/index
    xcpqc
    testing
+   continuous_integration
 
 Indices and tables
 ^^^^^^^^^^^^^^^^^^

docs/_sources/developer/index.rst

@@ -41,7 +41,7 @@ The Singularity command will create ``data_settings.yml`` in the current working
 
 The Docker command requires a few more parameters than the Singularity command:
 
-* ``--user $(id -u)`` is necessary so the generated files will be owned locally by the user running Docker rather than by root (the default).
+* ``--user $(id -u)`` is necessary so the generated files will be owned locally by the user running Docker rather than by ``c-pac_user`` (the default).
 * ``-v /path/to/data_config:/scratch`` binds your local ``data_config`` directory to ``/scratch`` on the Docker image, and
 * ``-w="/scratch"`` sets the current working directory on the Docker image to ``/scratch``.