added small entry for docker exec (#33989)

there's so much missing here (qwq)

guide/english/docker/docker-exec/index.md

@@ -0,0 +1,36 @@
+---
+title: Docker exec
+---
+
+## Docker exec
+
+`docker exec` allows you to run a command in a running container.  
+By command, any available command (inside of container) is meant,  
+allowing you to start/stop/execute any kind of routine and even some complex actions.  
+Also combined with args `-it` and `bash|sh|csh|zsh` (depending on container) allows you to enter a container, just like ssh-ing it.  
+(It'll throw you into your `WORKDIR`)  
+
+Example:
+```bash
+docker exec -it ee49f9048356 bash
+root@ee49f9048356 \ $
+```
+#### Reference
+```bash
+
+Usage:  docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
+
+Run a command in a running container
+
+Options:
+  -d, --detach               Detached mode: run command in the background
+      --detach-keys string   Override the key sequence for detaching a container
+  -e, --env list             Set environment variables
+  -i, --interactive          Keep STDIN open even if not attached
+      --privileged           Give extended privileges to the command
+  -t, --tty                  Allocate a pseudo-TTY
+  -u, --user string          Username or UID (format: <name|uid>[:<group|gid>])
+  -w, --workdir string       Working directory inside the container
+```
+
+[Documentation](https://docs.docker.com/engine/reference/commandline/exec/)