fix formatting of inline kbd macro example

Author: mojavelinux

docs/modules/ROOT/pages/ui-macro-styles.adoc

@@ -27,7 +27,7 @@ btn:[Save]
 
 == Keybinding
 
-A xref:antora:asciidoc:ui-macros.adoc#keybinding[keybinding] can be a single key (`+kbd:[F11]+`) or a sequence of keys (`+kbd:[Ctrl+F]`).
+A xref:antora:asciidoc:ui-macros.adoc#keybinding[keybinding] can be a single key (`+kbd:[F11]+`) or a sequence of keys (`+kbd:[Ctrl+F]+`).
 Here's the HTML that's generated for these two forms.
 
 [source,html]