finish up what is left, add link to homepage

Author: mireille-raad

_config.yml

@@ -46,6 +46,8 @@ navigation:
 dashboards:
   - title: CPython test compatibility 
     url: /pages/regression-tests-results.html
+  - title: What's left to add to RustPython
+    url: /pages/whats-left
 
 # Build settings
 theme: minima

_layouts/whats_left.html

@@ -16,7 +16,7 @@
 
 
 <div class="w-80 m-auto mt-2">
-    {{ page.content }}
+    {{ content }}
     <div class="section-title">What's Left: entire modules</div>
     <div class="column-count-is-2">
         <ol>

pages/whats-left.markdown

@@ -5,5 +5,10 @@ date:   2021-03-29 01:45:00 +0900
 categories: numbers
 ---
 
-<p>
-RustPython currently supports the full Python syntax. This is "what's left" from the Python Standard Library. For each module's details, check the <a href="https://docs.python.org/3/py-modindex.html">Python Module Index</a>. </p>
+RustPython currently supports the full Python syntax. This is "what's left" from the Python Standard Library.   
+For each module's details, check the [Python Module Index](https://docs.python.org/3/py-modindex.html).
+
+Note that not every module here is critical or feasible for RustPython to implement. For example, the `readline` Python module is heavily based around the API of GNU readline, but we use rustyline (a different readline implementation), so it probably wouldn't be worth the effort to emulate GNU
+readline on top of rustyline just to implement an infrequently used module.
+
+In addition, some modules may just be modules written in Python that we haven't copied over to the stdlib yet; always be sure to check whether a module is implemented in Python before trying to rewrite it in Rust. You can follow [these instructions](https://rustpython.github.io/blog/2020/04/04/how-to-contribute-by-cpython-unittest.html#add-a-new-unittest-file) for copying over files from CPython's Lib.