dovecot: Remove "experimental" qualifiers

dovecot support has been around for a release, has decent testing and
seems stable enough to remove the "experimental" qualifier.

etc/chasquid/chasquid.conf

@@ -71,3 +71,16 @@
 # If "<syslog>", log using the syslog (at MAIL|INFO priority).
 # Default: <syslog>
 #mail_log_path: "<syslog>"
+
+# Enable dovecot authentication.
+# If set to true, users not found in chasquid's user databases will be
+# authenticated via dovecot.
+# Default: false
+#dovecot_auth: false
+
+# Dovecot userdb and client socket paths.
+# Most of the time this is not needed, as chasquid will auto-detect their
+# location by searching standard paths.
+# Default: "" (autodetect)
+#dovecot_userdb_path: ""
+#dovecot_client_path: ""