template: move alternatives section below detailed design (#168)

XXXX-template.md

@@ -24,11 +24,6 @@ A brief summary of what the feature is.
 Why are we doing this? What use cases does it support? What is the expected
 outcome?
 
-## Alternatives Considered
-
-What alternative designs were considered and what pros/cons does this feature
-have relative to them?
-
 ## New Terminology
 
 Is there any new terminology introduced with this proposal?
@@ -50,6 +45,11 @@ document are to be interpreted as described in [RFC
 2119](https://www.ietf.org/rfc/rfc2119.txt) and [RFC
 8174](https://www.ietf.org/rfc/rfc8174.txt).
 
+## Alternatives Considered
+
+What alternative designs were considered and what pros/cons does this feature
+have relative to them?
+
 ## Impact
 
 How will the implemented proposal impacts dapp developers, validators, and core contributors?
@@ -66,4 +66,4 @@ Why should we not do this?
 ## Backwards Compatibility *(Optional)*
 
 Does the feature introduce any breaking changes? All incompatibilities and
-consequences should be listed.
+consequences should be listed.