Fix markup for bootstrap checks docs

This commit adds a missing backtick to the bootstrap check docs.

docs/reference/setup/bootstrap-checks.asciidoc

@@ -33,7 +33,7 @@ Elaticsearch instance to be in development mode if it does not bind
 transport to an external interface (the default), and is otherwise in
 production mode if it does bind transport to an external interface. Note
 that HTTP can be configured independently of transport via
-<<modules-http,`http.host>> and
+<<modules-http,`http.host`>> and
 <<modules-transport,`transport.tcp.host`>>; this can be useful for
 configuring a single instance to be reachable via HTTP for testing
 purposes without triggering production mode.