docs: document the possibility of zombie processes on ssh disconnect for :connect and :enter commands

Apparently terminating the ssh connection that runs 'docker exec' may result in a process leak as the signal isn't propagated properly (moby/moby#9098). Since we cannot fix this, we should document it so that users do not stumble upon the issue unawares.

Closes dokku/dokku-postgres#212

README.md

@@ -262,6 +262,8 @@ dokku postgres:connect <service>
 
 Connect to the service via the postgres connection tool:
 
+> NOTE: disconnecting from ssh while running this command may leave zombie processes due to moby/moby#9098
+
 ```shell
 dokku postgres:connect lollipop
 ```
@@ -275,6 +277,8 @@ dokku postgres:enter <service>
 
 A bash prompt can be opened against a running service. Filesystem changes will not be saved to disk.
 
+> NOTE: disconnecting from ssh while running this command may leave zombie processes due to moby/moby#9098
+
 ```shell
 dokku postgres:enter lollipop
 ```

subcommands/connect

@@ -7,6 +7,7 @@ source "$(dirname "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)")/functions"
 
 service-connect-cmd() {
   #E connect to the service via the $PLUGIN_COMMAND_PREFIX connection tool
+  #E > NOTE: disconnecting from ssh while running this command may leave zombie processes due to moby/moby#9098
   #E dokku $PLUGIN_COMMAND_PREFIX:connect lollipop
   #A service, service to run command against
   declare desc="connect to the service via the $PLUGIN_COMMAND_PREFIX connection tool"

subcommands/enter

@@ -8,6 +8,7 @@ source "$(dirname "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)")/functions"
 service-enter-cmd() {
   #E a bash prompt can be opened against a running service.
   #E filesystem changes will not be saved to disk.
+  #E > NOTE: disconnecting from ssh while running this command may leave zombie processes due to moby/moby#9098
   #E dokku $PLUGIN_COMMAND_PREFIX:enter lollipop
   #E you may also run a command directly against the service.
   #E filesystem changes will not be saved to disk.