Update help source files for Asciidoc 8.4.x.

xulmus/locale/en-US/gui.txt

@@ -1,11 +1,11 @@
-heading:Vimperator's{nbsp}GUI[gui]
+heading::Vimperator's{nbsp}GUI[gui]
 
 Although Xulmus offers the most frequently used Songbird functionality via
 Ex and Normal mode commands there may be times when directly accessing the GUI
 is required. There are commands for accessing the menu system, standard dialogs
 and the sidebar.
 
-section:Menus[menu]
+section::Menus[menu]
 
 |:emenu| +
 ||:emenu {menu}||
@@ -16,7 +16,7 @@ hierarchical path to the menu item with each submenu separated by a period.
 E.g. [c]:emenu File.Open File...[c]
 ________________________________________________________________________________
 
-section:Dialogs[dialogs]
+section::Dialogs[dialogs]
 
 |:addo| |:addons| +
 ||:addo[ns]||
@@ -68,7 +68,7 @@ Show progress of current downloads. Open the original Songbird download dialog
 in a new tab. Here, downloads can be paused, canceled and resumed.
 ________________________________________________________________________________
 
-section:Add-ons[extensions,add-ons]
+section::Add-ons[extensions,add-ons]
 
 |:exta| |:extadd| +
 ||:exta[dd] {file}||
@@ -119,7 +119,7 @@ Open the preferences dialog for an extension. If [!] is given, open a dialog,
 otherwise open a buffer. See also 'newtab'.
 ________________________________________________________________________________
 
-section:Sidebar[sidebar]
+section::Sidebar[sidebar]
 
 |:dpcl| |:dpclose| +
 ||:dpcl[ose] {pane}||
@@ -135,7 +135,7 @@ Open the specified display pane. {pane} is any of "service pane left", "service
 pane bottom", "content pane bottom" or "right sidebar".
 ________________________________________________________________________________
 
-section:Toolbars[toolbar]
+section::Toolbars[toolbar]
 
 |:tbs| |:tbshow| |:toolbars| |:toolbarshow| +
 ||:toolbarshow {name}||