Change the functions catalog link to https://catalog.kpt.dev/function-catalog/

https://catalog.kpt.dev/ mimics the start page of the documentation, therefore
confusing for the user to jump there.

Signed-off-by: Gergely Csatari <gergely.csatari@nokia.com>

Author: CsatariGergely

documentation/config.toml

@@ -176,5 +176,5 @@ enable = false
 
 [[menu.main]]
 name = "Functions Catalog"
-url = "https://catalog.kpt.dev/"
+url = "https://catalog.kpt.dev/function-catalog/"
 weight = 40