Merge pull request #13937 from bparees/newapp

clarify new-app language detection behavior

dev_guide/application_lifecycle/new_app.adoc

@@ -201,6 +201,20 @@ To use the *openshift/ruby-20-centos7:latest* container image stream with the so
 $ oc new-app openshift/ruby-20-centos7:latest~/home/user/code/my-ruby-app
 ----
 
+====
+[NOTE]
+Language detection requires the git client be locally installed so that your repository
+can be cloned and inspected.  If git is not available, you can avoid the language detection
+step by specifying the builder image to use with your repository via the `<image>~<repository>` syntax.
+
+Using the `-i <image> <repository>` invocation requires that `new-app` attempt to clone `repository` in
+order to determine what type of artifact it is, so this will fail if git is not available.
+
+Similarly using the `-i <image> --code <repository>` invocation requires `new-app` clone `repository`
+in order to determine whether `image` should be used as a builder for the source code, or deployed
+separately, as in the case of a database image.
+====
+
 [[specifying-an-image]]
 
 === Creating an Application From an Image