docs: add some proxies docs

docs/user/proxies.rst

@@ -1,2 +1,29 @@
 Web Proxies
-===========
+===========
+
+Web proxies provide alternate URLs to access censored resources.
+These can be accessed through a normal web browser.
+They use frequently changing URLs to evade censorship.
+Some functionality on more complex websites may not work fully.
+The URLs will have a limited lifetime as, once discovered, they can be blocked by censors.
+
+This assumption of a limited lifetime is built-in to the system, allowing for automated block detection to trigger the
+deployment of new URLs, and for the :doc:`distribution lists <lists>` to allow applications and end-users to discover
+new URLs.
+
+Web Origins
+-----------
+
+Static Origins
+--------------
+
+These have not yet been implemented.
+
+Simple Proxies
+--------------
+
+Smart Proxies
+-------------
+
+Where a simple proxy leads to a broken user experience, it may be necessary to use a smart proxy to mitigate the
+brokenness.