Document updated main/nightly component configuration for apt-test

docs/workstation_development.rst

@@ -60,7 +60,9 @@ Automatic updates
 Double-clicking the “SecureDrop” desktop icon will launch a preflight
 updater that applies any necessary updates to VMs, and may prompt a
 reboot. In a development environment, this will install the latest
-nightly packages, and the latest RPM published to ``yum-test``.
+nightly packages (unless there is a more recent release candidate
+on ``apt-test`` in ``main``), and the latest RPM published to 
+``yum-test``.
 
 Manually updating dom0 code
 ---------------------------

docs/workstation_setup.rst

@@ -50,10 +50,15 @@ instructions:
 
 -  The development environment uses the ``yum-test.securedrop.org`` and
    ``apt-test.freedom.press`` repositories, and is configured to use the
-   ``nightly`` component for apt package. It does not alter power
-   management settings on your laptop to prevent suspension to disk (a
-   security measure for production environments, which the staging
-   environment preserves to be more faithful to prod-like settings).
+   ``nightly`` and ``main`` components for apt packages. This means it
+   will install nightly packages, unless a package is only available
+   in ``main``, or a more recent version has been published there,
+   e.g., a release candidate.
+
+   This configuration does not alter your management settings on your
+   laptop to prevent suspension to disk (a security measure for
+   production environments, which the staging environment preserves
+   to be more faithful to prod-like settings).
 
 -  The production environment uses ``yum.securedrop.org`` and
    ``apt.freedom.press`` repositories, verified using the production