Change error messages that say 'ddev add' to 'ddev start' (#109)

README.md

@@ -2,7 +2,7 @@
 
 The purpose of *ddev* is to support developers with a local copy of a site for development purposes. It runs the site in Docker containers.
 
-You can see all "ddev" usages using the help commands, like `ddev -h`, `ddev add -h`, etc.
+You can see all "ddev" usages using the help commands, like `ddev -h`, `ddev start -h`, etc.
 
 ## Key prerequisites
 - A working [docker install](https://www.docker.com/community-edition)

cmd/ddev/cmd/dev_sequelpro.go

@@ -26,7 +26,7 @@ var LocalDevSequelproCmd = &cobra.Command{
 		nameContainer := fmt.Sprintf("%s-db", app.ContainerName())
 
 		if !dockerutil.IsRunning(nameContainer) {
-			Failed("App not running locally. Try `ddev add`.")
+			Failed("App not running locally. Try `ddev start`.")
 		}
 
 		mysqlContainer, err := dockerutil.GetContainer(nameContainer)

cmd/ddev/cmd/logs.go

@@ -29,11 +29,11 @@ var LocalDevLogsCmd = &cobra.Command{
 		nameContainer := fmt.Sprintf("%s-%s", app.ContainerName(), serviceType)
 
 		if !dockerutil.IsRunning(nameContainer) {
-			Failed("App not running locally. Try `ddev add`.")
+			Failed("App not running locally. Try `ddev start`.")
 		}
 
 		if !platform.ComposeFileExists(app) {
-			Failed("No docker-compose yaml for this site. Try `ddev add`.")
+			Failed("No docker-compose yaml for this site. Try `ddev start`.")
 		}
 
 		cmdArgs := []string{