Fix link to nearest readmode

Author: jmikola

source/applications/replication.txt

@@ -301,7 +301,7 @@ behavior <replica-set-read-preference-behavior>`. See also the
    The driver reads from the *nearest* member of the :term:`set <replica
    set>` according to the :ref:`member selection
    <replica-set-read-preference-behavior-nearest>` process. Reads in
-   the readmode:`nearest` mode do not consider the member's
+   the :readmode:`nearest` mode do not consider the member's
    *type*. Reads in :readmode:`nearest` mode may read from both
    primaries and secondaries.