V1 tag and deprecation (#240)

* deprecation warning

* Update message and CLI call

* Add to readme as well

README.md

@@ -26,11 +26,20 @@ $ conda install cookiecutter
 ### To start a new project, run:
 ------------
 
-    cookiecutter https://github.com/drivendata/cookiecutter-data-science
+    cookiecutter -c v1 https://github.com/drivendata/cookiecutter-data-science
 
 
 [![asciicast](https://asciinema.org/a/244658.svg)](https://asciinema.org/a/244658)
 
+### New version of Cookiecutter Data Science
+------------
+Cookiecutter data science is moving to v2 soon, which will entail using
+the command `ccds ...` rather than `cookiecutter ...`. The cookiecutter command
+will continue to work, and this version of the template will still be available.
+To use the legacy template, you will need to explicitly use `-c v1` to select it.
+Please update any scripts/automation you have to append the `-c v1` option (as above),
+which is available now.
+
 
 ### The resulting directory structure
 ------------

hooks/pre_gen_project.py

@@ -0,0 +1,22 @@
+def deprecation_warning():
+    print("""
+
+=============================================================================
+*** DEPRECATION WARNING ***
+
+Cookiecutter data science is moving to v2 soon, which will entail using
+the command `ccds ...` rather than `cookiecutter ...`. The cookiecutter command
+will continue to work, and this version of the template will still be available.
+To use the legacy template, you will need to explicitly use `-c v1` to select it.
+
+Please update any scripts/automation you have to append the `-c v1` option,
+which is available now.
+
+For example:
+    cookiecutter -c v1 https://github.com/drivendata/cookiecutter-data-science
+=============================================================================
+
+    """)
+
+
+deprecation_warning()