Doc: Adjust output for \techpreview macro

The output generated for entities using the \preliminary QDoc command
can now be customized via documentation configuration variables.

Repurpose \preliminary for marking entities as being in 'technology
preview' state, and turn the \techpreview macro into a direct alias
for \preliminary.

Task-number: QTBUG-142344
Change-Id: Icb80d6b67514c1e6ba594bbaeb20b6a06e3154d3
Reviewed-by: Topi Reinio <topi.reinio@qt.io>

Author: toreinio

doc/global/macros.qdocconf

@@ -174,10 +174,11 @@ macro.cmakepropertyiosonly = "\\note This property is used only if targeting iOS
 macro.cmakevariableiosonly = "\\note This variable is used only if targeting iOS."
 
 macro.qtpolicydeprecatedbehavior = "\\note The \\c{OLD} behavior of a policy is deprecated, and may be removed in the future."
-#Appends the tech preview link to the brief sentence and adds to tech_preview
-#group.
-#Must be placed directly under a \brief command
-macro.techpreview = "(Technical preview)\n\n\\meta status {Technical preview}\n\\ingroup tech_preview\n"
+
+# Set preliminary status as 'Technology preview'
+preliminary             = "Technology preview"
+preliminary.description = "This \1 is in technology preview and is subject to change."
+macro.techpreview       = \\preliminary
 
 include(grid.qdocconf)
 include(cpp-doc-macros.qdocconf)