docs/reference: Remove double 'are' in glossary.

docs/reference/glossary.rst

@@ -120,7 +120,7 @@ Glossary
         <https://github.com/micropython/micropython-lib>`_ which provides
         implementations for many modules from CPython's standard library.
 
-        Some of the modules are are implemented in pure Python, and are able to
+        Some of the modules are implemented in pure Python, and are able to
         be used on all ports. However, the majority of these modules use
         :term:`FFI` to access operating system functionality, and as such can
         only be used on the :term:`MicroPython Unix port` (with limited support