docs: add See Also for description of login/logout and start/stop

make them reference to each other.

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>

docs/man/docker-login.1.md

@@ -36,6 +36,9 @@ login to a private registry you can specify this by adding the server name.
 
     # docker login localhost:8080
 
+# See also
+**docker-logout(1)** to log out from a Docker registry.
+
 # HISTORY
 April 2014, Originally compiled by William Henry (whenry at redhat dot com)
 based on docker.com source material and internal work.

docs/man/docker-logout.1.md

@@ -22,6 +22,9 @@ There are no available options.
 
     # docker logout localhost:8080
 
+# See also
+**docker-login(1)** to register or log in to a Docker registry server.
+
 # HISTORY
 June 2014, Originally compiled by Daniel, Dao Quang Minh (daniel at nitrous dot io)
 July 2014, updated by Sven Dowideit <SvenDowideit@home.org.au>

docs/man/docker-start.1.md

@@ -25,6 +25,9 @@ Start a stopped container.
 **-i**, **--interactive**=*true*|*false*
    Attach container's STDIN. The default is *false*.
 
+# See also
+**docker-stop(1)** to stop a running container.
+
 # HISTORY
 April 2014, Originally compiled by William Henry (whenry at redhat dot com)
 based on docker.com source material and internal work.

docs/man/docker-stop.1.md

@@ -21,6 +21,9 @@ Stop a running container (Send SIGTERM, and then SIGKILL after
 **-t**, **--time**=10
    Number of seconds to wait for the container to stop before killing it. Default is 10 seconds.
 
+#See also
+**docker-start(1)** to restart a stopped container.
+
 # HISTORY
 April 2014, Originally compiled by William Henry (whenry at redhat dot com)
 based on docker.com source material and internal work.