Add basic documentation for TLS flags

Author: md5

README.md

@@ -73,7 +73,7 @@ $ docker run -d --name nginx-gen --volumes-from nginx \
 ### Usage
 ```
 $ docker-gen
-Usage: docker-gen [-config file] [-watch=false] [-notify="restart xyz"] [-notify-sighup="nginx-proxy"] [-interval=0] [-endpoint tcp|unix://..] <template> [<dest>]
+Usage: docker-gen [-config file] [-watch=false] [-notify="restart xyz"] [-notify-sighup="nginx-proxy"] [-interval=0] [-endpoint tcp|unix://..] [-tlsverify] [-tlscert file] [-tlskey file] [-tlscacert file] <template> [<dest>]
 ```
 
 *Options:*
@@ -88,6 +88,10 @@ Usage: docker-gen [-config file] [-watch=false] [-notify="restart xyz"] [-notify
   -notify-sighup="": send HUP signal to container.  Equivalent to `docker kill -s HUP container-ID`
   -only-exposed=false: only include containers with exposed ports
   -only-published=false: only include containers with published ports (implies -only-exposed)
+  -tlscacert="": path to TLS CA certificate file
+  -tlscert="": path to TLS client certificate file
+  -tlskey="": path to TLS client key file
+  -tlsverify=false: verify docker daemon's TLS certicate
   -version=false: show version
   -watch=false: run continuously and monitors docker container events.  When containers are started
                 or stopped, the template is regenerated.