docs(guides): rearranges menu order

docs/sources/guides/whats-new-in-v3-1.md

@@ -7,7 +7,7 @@ type = "docs"
 name = "Version 3.1"
 identifier = "v3.1"
 parent = "whatsnew"
-weight = 1
+weight = 5
 +++
 
 # What's New in Grafana v3.1

docs/sources/guides/whats-new-in-v3.md

@@ -7,7 +7,7 @@ type = "docs"
 name = "Version 3.0"
 identifier = "v3.0"
 parent = "whatsnew"
-weight = 2
+weight = 6
 +++
 
 # What's New in Grafana v3.0

docs/sources/guides/whats-new-in-v4.md

@@ -7,7 +7,7 @@ type = "docs"
 name = "Version 4.0"
 identifier = "v4.0"
 parent = "whatsnew"
-weight = -1
+weight = 4
 +++
 
 # What's New in Grafana v4.0