Update README for elastic/security (elastic#430)

Add a few links to external sources and places in source code.

elastic/security/README.md

@@ -136,7 +136,7 @@ This challenge executes indexing and querying sequentially. Queries will be issu
 
 ### Generate source events for detection rules (generate-alerts-source-events)
 
-This challenge is a demo usage of Geneve via the `events-emitter-source` parameter source, it generates source events but does not interact with anything else. It's executed as part of the `it/test_security.py` integration tests.
+This challenge is a demo usage of [Geneve](https://github.com/elastic/geneve) via the `events-emitter-source` [parameter source](https://github.com/elastic/rally-tracks/blob/master/elastic/security/parameter_sources/events_emitter.py), it generates source events but does not interact with anything else. It's executed as part of the [it/test_security.py](https://github.com/elastic/rally-tracks/blob/master/it/test_security.py) integration tests. Currently, Geneve is pinned to version [v0.2.0](https://github.com/elastic/rally-tracks/blob/master/elastic/security/track.json#L410). This is the only challenge that depends on Geneve and pyyaml (Geneve requires pyyaml).
 
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