Add missing backtick to close literal role in configuration.rst (#12547)

Author: rffontenelle

doc/usage/configuration.rst

@@ -259,7 +259,7 @@ General configuration
 
    A URL to cross-reference :rst:role:`manpage` roles.
    If this is defined to ``https://manpages.debian.org/{path}``,
-   the :literal:`:manpage:`man(1)` role will link to
+   the :literal:`:manpage:`man(1)`` role will link to
    <https://manpages.debian.org/man(1)>.
    The patterns available are: