docs: improve autoupdater explanation

docs/features/autoupdater.rst

@@ -11,14 +11,19 @@ during development), but it can be enabled by setting the variable GLUON_BRANCH
 to override the default branch set in the set in the site configuration.
 
 A manifest file for the updater can be generated with `make manifest`. A signing script (using
-ecdsautils) can by found in the `contrib` directory. When creating the manifest, ``GLUON_PRIORITY`` can
-be set on the command line, or it can be taken from the ``site.mk``.
+``ecdsautils``) can by found in the `contrib` directory. When creating the manifest, the 
+``PRIORITY`` value may be defined by setting ``GLUON_PRIORITY`` on the command line or in ``site.mk``.
 
-The priority defines the maximum number of days that may pass between releasing an update and installation
-of the images. The update probability will start at 0 after the release time mentioned in the manifest
-and then slowly rise to 1 up to the point when the number of days given by the priority has passed.
+``GLUON_PRIORITY`` defines the maximum number of days that may pass between releasing an update and installation
+of the images. The update probability will start at 0 after the release time declared in the manifest file
+by the variable DATE and then slowly rise up to 1 when ``GLUON_PRIORITY`` days have passed. The autoupdater checks
+for updates hourly (at a random minute of the hour), but usually only updates during its run between
+4am and 5am, except when the whole ``GLUON_PRIORITY`` days and another 24 hours have passed.
 
-The priority may be an integer or a decimal fraction.
+``GLUON_PRIORITY`` may be an integer or a decimal fraction.
+
+Automated nightly builds
+------------------------
 
 A fully automated nightly build could use the following commands:
 
@@ -71,11 +76,9 @@ These commands can be used on a node:
 
    # Force update check, even when the updater is disabled
    autoupdater -f
-   
+
 ::
 
-   # If fallback is true the updater will perform an update only if 
-   # the timespan given by the priority and another 24h have passed
+   # If fallback is true the updater will perform an update only if the timespan 
+   # PRIORITY days (as defined in the manifest) and another 24h have passed
    autoupdater --fallback
-
-