PEP 776: Some followup edits (#4309)

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: hoodmane

peps/pep-0776.rst

@@ -72,6 +72,23 @@ Packaging Goals
 Emscripten Platform Information
 ===============================
 
+"Pyodide" vs "Emscripten Python"
+--------------------------------
+
+For the sake of this document, we use the term "Emscripten Python" to refer to
+the Emscripten Python maintained in the ``python/cpython`` repository, without
+any downstream additions. We contrast the features present in Emscripten Python
+to the features present in Pyodide.
+
+Pyodide is maintained `on GitHub <https://github.com/pyodide/pyodide>`__ and
+distributed via `jsDelivr <https://www.jsdelivr.com/oss-cdn/pyodide>`__, `npm
+<https://www.npmjs.com/package/pyodide>`__, and `GitHub releases
+<https://github.com/pyodide/pyodide/releases>`__.
+
+Emscripten Python is not distributed, but it is possible to build `by following
+the instructions in the devguide
+<https://devguide.python.org/getting-started/setup-building/#emscripten>`__
+
 Background on Emscripten
 ------------------------
 
@@ -731,7 +748,9 @@ Because Emscripten supports POSIX, a significant number of tasks can be achieved
 using the ``os`` module. However, many fundamental operations in JavaScript
 runtimes are not possible via POSIX APIs. Pyodide's approach is to specify a
 mapping between the JavaScript object model and the Python object model and a
-calling convention that allows high level bidirectional integration.
+calling convention that allows high level bidirectional integration. `See the
+Pyodide documentation
+<https://pyodide.org/en/stable/usage/type-conversions.html>`__.
 
 Asyncio
 ~~~~~~~