updates per comments

docs/source/specification.rst

@@ -4,17 +4,27 @@
 The Reproducible Execution Environment Specification
 ====================================================
 
-repo2docker scans a repository for particular :ref:`config_files`, such
-as ``requirements.txt`` or ``REQUIRE``. The collection of files and their contents
-that repo2docker uses is known as the **Reproducible Execution Environment Specification**.
+repo2docker scans a repository for particular :ref:`config-files`, such
+as ``requirements.txt`` or ``REQUIRE``. The collection of files, their contents,
+and the resulting actions that repo2docker takes is known
+as the **Reproducible Execution Environment Specification** (or REES).
 
-The goal of the REE Specification is to provide a structure that is clearly-defined and that
-can be extended to accomodate more components of a reproducible workflow.
+The goal of the REES is to automate and encourage existing community best practices
+for reproducible computational environments. This includes installing
+community-standard specification files such as ``requirements.txt`` or ``REQUIRE`` using
+standard tools such as ``pip`` or ``conda`` or ``apt``. While repo2docker automates the
+creation of the environment, a human should be able to look at a REES-compliant
+repository and reproduce the environment using common, clear steps without
+repo2docker software.
 
 Currently, the definition of the REE Specification is the following:
 
-> Any collection of files taken from the :ref:`config_files`
-> list, placed either in the root of a folder or in a sub-folder called either ``binder/`` or ``.binder/``.
+    Any collection of files taken from the :ref:`config-files`
+    list, placed either in the root of a folder or in a sub-folder called
+    either ``binder/`` or ``.binder/``.
 
-In the future, the repo2docker team plans to formalize this specification into a pattern
-that can also be followed in other ways, such as by creating a JSON or YAML file.
+For example, the REES recognises ``requirements.txt`` as a valid config file.
+The file format is as defined by the ``requirements.txt`` standard of the Python
+community. A REES-compliant tool will install a Python interpreter (of unspecified version)
+and perform the equivalent action of ``pip install -r requirements.txt`` so that the
+user can afterwards run python and use the packages installed.