DOC: remove duplicate list of plugins

Author: ColmTalbot

docs/plugins.txt

@@ -51,17 +51,6 @@ for creating sampler plugins on GitHub.
     the plugin (e.g. 'nest', 'mcmc') as this may lead to naming conflicts.
 
 
-Sampler plugin library
-----------------------
-
-This is a list of known sampler plugins. if you don't see your plugin listed
-here, we encourage you to open a
-`pull request <https://github.com/bilby-dev/bilby/compare>`_ to add it.
-
-- :code:`nessai-bilby`: https://github.com/bilby-dev/nessai-bilby
-- :code:`pypolychord-bilby`: https://github.com/bilby-dev/pypolychord-bilby
-
-
 Bilby-native samplers
 ---------------------