docs: Correct title for rolling-release "latest" docs (#1713)

Update title to "VyOS rolling release (current)" to replace
the misleading "VyOS 1.5.x (circinus) documentation"
and keep wording consistent with other pages.

Author: alexandr-san4ez

docs/conf.py

@@ -130,6 +130,11 @@
 # pixels large.
 html_favicon = '_static/images/vyos-logo-icon.png'
 
+# The "title" for HTML documentation generated with Sphinx's own templates.
+# This is appended to the `<title>` tag of individual pages, and used
+# in the navigation bar as the "topmost" element.
+html_title = f'{project} rolling release (current)'
+
 # -- Options for HTMLHelp output ---------------------------------------------
 
 # Output file base name for HTML help builder.