Remove useless comments and remove duplicate section in the example configs

config.yml.example.s3

@@ -6,7 +6,6 @@ development: &defaults
     access_key_id: ""
     secret_key_id: ""
     bucket: "test-bucket"
-  # Redis is needed for the swift backend
   redis:
     host: localhost
     port: 6379
@@ -19,9 +18,6 @@ test:
     access_key_id: ""
     secret_key_id: ""
     bucket: "test-bucket"
-  redis:
-    host: localhost
-    port: 6379
 
 staging:
   <<: *defaults

config.yml.example.swift

@@ -1,9 +1,7 @@
 development: &defaults
   maintenance: false
-  # uncomment this section
   swift: &swift_defaults
     host: "https://swift.example.com"
-  # Redis is needed for the swift backend
   redis:
     host: localhost
     port: 6379
@@ -12,9 +10,6 @@ test:
   <<: *defaults
   swift:
     host: "https://swift.example.com"
-  redis:
-    host: localhost
-    port: 6379
 
 staging:
   <<: *defaults