plugin/hosts: make hosts plugin cursive
nit-picking PR, when using the name of the plugin make it cursive.
## Description
-The hosts plugin is useful for serving zones from a `/etc/hosts` file. It serves from a preloaded
+The *hosts* plugin is useful for serving zones from a `/etc/hosts` file. It serves from a preloaded
file that exists on disk. It checks the file for changes and updates the zones accordingly. This
plugin only supports A, AAAA, and PTR records. The hosts plugin can be used with readily
available hosts files that block access to advertising servers.
