Unify missing app error messages

plugins/apps/commands

@@ -9,7 +9,7 @@ case "$1" in
 
   apps:create)
     if [[ -z $2 ]]; then
-      echo "Please specify an app to create"
+      echo "Please specify an app to run the command on"
       exit 1
     fi
     APP="$2"
@@ -24,7 +24,7 @@ case "$1" in
 
   apps:destroy)
     if [[ -z $2 ]]; then
-      echo "Please specify an app to delete"
+      echo "Please specify an app to run the command on"
       exit 1
     fi
     APP="$2"; IMAGE="dokku/$APP";

plugins/config/commands

@@ -4,7 +4,7 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # Check if name is specified
 if [[ $1 == config ]] || [[ $1 == config:* ]]; then
   if [[ -z $2 ]]; then
-    echo "You must specify an app name"
+    echo "Please specify an app to run the command on"
     exit 1
   else
     APP="$2"

plugins/nginx-vhosts/commands

@@ -4,7 +4,7 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 case "$1" in
   nginx:import-ssl)
     if [[ -z $2 ]]; then
-      echo "Please specify an app to create"
+      echo "Please specify an app to run the command on"
       exit 1
     fi
     APP="$2"