Add documentation for no-strict-offset-reset (#459)

Author: untitaker

docs/source/index.rst

@@ -14,3 +14,4 @@ Contents:
    dlqs
    backpressure
    metrics
+   parameters

docs/source/parameters.rst

@@ -0,0 +1,17 @@
+==========================
+Common consumer parameters
+==========================
+
+Many consumers expose a CLI interface on top of arroyo, but in the case of
+Sentry's own consumers they all look very similar. This page is there to
+explain some of them.
+
+* ``--no-strict-offset-reset``: Arroyo, by default, overwrites rdkafka's offset
+  reset behavior to always error when the underlying offset is out of range.
+  That means ``auto-offset-reset: latest`` will reset to latest when the offset
+  does not yet exist, but still error if the offset is out of range. This is to
+  prevent accidental data loss during incident response, when a consumer has
+  been backlogged for a very long time.
+
+  In arroyo the parameter can be passed as kafka configuration parameter
+  ``arroyo.strict.offset.reset``.