Update README.md (#649)

README.md

@@ -8,7 +8,7 @@ This is the official [Heroku buildpack](https://devcenter.heroku.com/articles/bu
 
 Recommended web frameworks include **Django** and **Flask**. The recommended webserver is **Gunicorn**. There are no restrictions around what software can be used (as long as it's pip-installable). Web processes must bind to `$PORT`, and only the HTTP protocol is permitted for incoming connections.
 
-Some Python packages with obscure C dependencies are [not compatible](https://devcenter.heroku.com/articles/python-c-deps).
+Python packages with C dependencies that are not [available on the stack image](https://devcenter.heroku.com/articles/stack-packages) are generally not supported, unless `manylinux` wheels are provided by the package maintainers (common). For recommended solutions, check out [this article](https://devcenter.heroku.com/articles/python-c-deps) for more information. 
 
 See it in Action
 ----------------
@@ -16,7 +16,7 @@ See it in Action
 Deploying a Python application couldn't be easier:
 
     $ ls
-    Pipfile		Procfile	web.py
+    Pipfile		Pipfile.lock	Procfile	web.py
 
     $ heroku create --buildpack heroku/python
 
@@ -41,12 +41,7 @@ You can also specify the latest production release of this buildpack for upcomin
 Specify a Python Runtime
 ------------------------
 
-Specific versions of the Python runtime can be specified with a `runtime.txt` file:
-
-    $ cat runtime.txt
-    python-2.7.14
-
-Or, with a `Pipfile.lock` (generated from the following `Pipfile`):
+Specific versions of the Python runtime can be specified in your `Pipfile`:
 
     [requires]
     python_version = "2.7"
@@ -56,9 +51,12 @@ Or, more specifically:
     [requires]
     python_full_version = "2.7.14"
 
+Or, with a `runtime.txt` file:
+
+    $ cat runtime.txt
+    python-2.7.14
+
 Runtime options include:
 
 - `python-3.6.4`
 - `python-2.7.14`
-- `pypy-5.7.1` (unsupported, experimental)
-- `pypy3-5.5.1` (unsupported, experimental)