conan runner docs added

reference.rst

@@ -17,3 +17,4 @@ Reference
    reference/environment
    reference/binary_model
    reference/conan_server
+   reference/runners

reference/runners.rst

@@ -0,0 +1,17 @@
+.. _reference_runners:
+
+Runners
+=======
+
+Runners are the way to run Conan remotely and transparently just by modifying the host profile. There are three requirements to be able to use the feature:
+
+- Installing a version of conan with runner dependencies ``pip install conan[runners]``. 
+- Install the tools to run each of the runners (``docker``).
+- Add the ``[runner]`` section defined in the documentation of each runner to the host profile.
+
+Runners:
+
+.. toctree::
+    :maxdepth: 1
+
+    runners/docker