[doc] xref to hostfile discussion (#604)

* [doc] xref to hostfile discussion

wasn't clear where to find what was meant by `hostfile` - so adding a link to where it's discussed.

* remove whitespace

docs/_pages/features.md

@@ -28,7 +28,8 @@ deepspeed --hostfile=<hostfile> \
 	<client_entry.py> <client args> \
 	--deepspeed --deepspeed_config ds_config.json
 ```
-The script `<client_entry.py>` will execute on the resources specified in `<hostfile>`.
+The script `<client_entry.py>` will execute on the resources specified in
+[`<hostfile>`](/getting-started/#resource-configuration-multi-node).
 
 ## Pipeline Parallelism
 DeepSpeed provides [pipeline parallelism](/tutorials/pipeline/) for memory-