[branding] [welcome] Adjust documentation for welcome-overrides

src/branding/default/branding.desc

@@ -58,7 +58,8 @@ windowSize: 800px,520px
 # if it contains substitutions, or you'll get YAML exceptions.
 #
 # The *Url* entries are used on the welcome page, and they
-# are visible as buttons there if the corresponding *show* keys are set.
+# are visible as buttons there if the corresponding *show* keys
+# are set to "true" (they can also be overridden).
 strings:
     productName:         "@{NAME}"
     shortProductName:    Generic

src/modules/welcome/welcome.conf

@@ -7,7 +7,11 @@
 # can check requirements for installation.
 ---
 # Display settings for various buttons on the welcome page.
-# The URLs themselves come from branding.desc
+# The URLs themselves come from branding.desc is the setting
+# here is "true". If the setting is false, the button is hidden.
+# The setting can also be a full URL which will then be used
+# instead of the one from the branding file, or empty or not-set
+# which will hide the button.
 showSupportUrl:         true
 showKnownIssuesUrl:     true
 showReleaseNotesUrl:    true