Fix a couple of typos in the docs of `docker attach`

This fix fixed a couple of typos in the docs of `docker attach`:
docs/reference/commandline/attach.md
man/docker-attach.1.md

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

docs/reference/commandline/attach.md

@@ -53,7 +53,7 @@ foreground over a slow client connection. Instead, users should use the
 
 If you want, you can configure an override the Docker key sequence for detach.
 This is useful if the Docker default sequence conflicts with key sequence you
-use for other applications. There are two ways to defines a your own detach key
+use for other applications. There are two ways to define your own detach key
 sequence, as a per-container override or as a configuration property on  your
 entire configuration.
 

man/docker-attach.1.md

@@ -45,7 +45,7 @@ attaching to a tty-enabled container (i.e.: launched with `-t`).
 
 If you want, you can configure an override the Docker key sequence for detach.
 This is useful if the Docker default sequence conflicts with key sequence you
-use for other applications. There are two ways to defines a your own detach key
+use for other applications. There are two ways to define your own detach key
 sequence, as a per-container override or as a configuration property on  your
 entire configuration.