Add section about conflict with snap version of docker

Author: TheGuit

content/manuals/engine/daemon/troubleshoot.md

@@ -35,6 +35,7 @@ This error may indicate:
   running the command again.
 - Your Docker client is attempting to connect to a Docker daemon on a different
   host, and that host is unreachable.
+- You have multiple Docker engine that run on your system (eg. snap & docker-ce).
 
 ### Check whether Docker is running
 

content/manuals/engine/install/ubuntu.md

@@ -92,6 +92,26 @@ automatically removed when you uninstall Docker. If you want to start with a
 clean installation, and prefer to clean up any existing data, read the
 [uninstall Docker Engine](#uninstall-docker-engine) section.
 
+#### Uninstall snap version
+
+Verify if you have snap version of Docker :
+
+```console
+snap list | grep docker
+```
+
+If you have this kind of result : 
+```text
+docker                     27.2.0                      2963      latest/stable    canonical**     -
+```
+
+Disable and remove the snap :
+```console
+sudo snap disable docker && sudo snap remove docker --purge
+```
+
+Then reboot.
+
 ## Installation methods
 
 You can install Docker Engine in different ways, depending on your needs: