Add the all option to kill command

Signed-off-by: utam0k <[email protected]>

Author: utam0k

runtime.md

@@ -135,6 +135,11 @@ This operation MUST [generate an error](#errors) if it is not provided the conta
 Attempting to send a signal to a container that is neither [`created` nor `running`](#state) MUST have no effect on the container and MUST [generate an error](#errors).
 This operation MUST send the specified signal to the container process.
 
+### <a name="runtimeKillAll" />KillAll
+`kill <container-id> <signal> <all>`
+
+Kill all the processes in the container.
+
 ### <a name="runtimeDelete" />Delete
 `delete <container-id>`