Fix typo in sample output

Changed `ICONTAINER ID` to `CONTAINER ID`.

Signed-off-by: Remy Suen <remy.suen@gmail.com>

docs/reference/commandline/commit.md

@@ -74,7 +74,7 @@ svendowideit/testimage            version3            f5283438590d        16 sec
 ```bash
 $ docker ps
 
-ICONTAINER ID       IMAGE               COMMAND             CREATED             STATUS              PORTS              NAMES
+CONTAINER ID       IMAGE               COMMAND             CREATED             STATUS              PORTS              NAMES
 c3f279d17e0a        ubuntu:12.04        /bin/bash           7 days ago          Up 25 hours                            desperate_dubinsky
 197387f1b436        ubuntu:12.04        /bin/bash           7 days ago          Up 25 hours                            focused_hamilton