Update GitHub templates to match arrow-rs versions

Author: andygrove

.github/ISSUE_TEMPLATE/feature_request.md

@@ -7,8 +7,9 @@ assignees: ''
 
 ---
 
-**Is your feature request related to a problem? Please describe.**
-A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] 
+(This section helps Arrow developers understand the context and *why* for this feature, in addition to  the *what*)
 
 **Describe the solution you'd like**
 A clear and concise description of what you want to happen.

.github/pull_request_template.md

@@ -4,6 +4,10 @@ We generally require a GitHub issue to be filed for all bug fixes and enhancemen
 
 Closes #.
 
+ # Rationale for this change
+ Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed.
+ Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes.  
+
 # What changes are included in this PR?
 
 There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR.
@@ -13,4 +17,3 @@ There is no need to duplicate the description in the issue here but it is someti
 If there are user-facing changes then we may require documentation to be updated before approving the PR.
 
 If there are any breaking changes to public APIs, please add the `breaking change` label.
-