make chapter name reflect file name

Personally I think this makes more sense anyway.

docs/SUMMARY.md

@@ -3,7 +3,7 @@
 - [Introduction](introduction.md)
 
 - [Example configuration](configuration.md)
-- [Deployment options](deploying.md)
+- [Deploying](deploying.md)
     - [Generic](deploying/generic.md)
     - [Debian](deploying/debian.md)
     - [Docker](deploying/docker.md)

docs/deploying.md

@@ -1,3 +1,3 @@
-# Deployment options
+# Deploying
 
 This chapter describes various ways to deploy Conduit.