PEP 776: Emscripten support (#4307)

Co-authored-by: Hugo van Kemenade <[email protected]>
Co-authored-by: Jelle Zijlstra <[email protected]>
Co-authored-by: Adam Turner <[email protected]>
Co-authored-by: Brett Cannon <[email protected]>

Author: 5 people

.github/CODEOWNERS

@@ -654,7 +654,7 @@ peps/pep-0772.rst  @warsaw @pradyunsg
 peps/pep-0773.rst  @zooba
 peps/pep-0774.rst  @savannahostrowski
 peps/pep-0775.rst  @encukou
-# ...
+peps/pep-0776.rst  @hoodmane @ambv
 peps/pep-0777.rst  @warsaw
 # ...
 peps/pep-0779.rst  @Yhg1s @colesbury @mpage