Add link to Runnel in README

Author: mjwestcott

README.md

@@ -64,3 +64,8 @@ async def bar(x):
 
 await bar.delay(5)
 ```
+
+### See also
+
+If you need to ensure that all tasks for a given key are processed in-order,
+please see our sister project [Runnel](https://github.com/mjwestcott/runnel).

pyproject.toml

@@ -2,6 +2,8 @@
 name = "fennel"
 version = "0.3.0"
 description = "A task queue for Python based on Redis Streams."
+readme = "README.md"
+keywords = ["task", "queue", "background", "redis", "async"]
 authors = ["Matt Westcott <m.westcott@gmail.com>"]
 license = "MIT"
 homepage = "https://fennel.dev"