Update feature.yml (#223)

## Why this should be merged
Non-unique IDs in feature-request template body.

## How this works
Makes IDs unique. See
[here](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/common-validation-errors-when-creating-issue-forms#body-must-have-unique-ids).

## How this was tested

[Inspection of GitHub preview](https://github.com/ava-labs/libevm/blob/michaelkaplan13/fix-feature-issue-template/.github/ISSUE_TEMPLATE/feature.yml)

Signed-off-by: Michael Kaplan <55204436+michaelkaplan13@users.noreply.github.com>

Author: michaelkaplan13

.github/ISSUE_TEMPLATE/feature.yml

@@ -10,6 +10,6 @@ body:
     validations:
       required: true
   - type: textarea
-    id: description
+    id: approach-and-alternatives
     attributes:
-      label: "How would you recommend implementing it?"
+      label: "Recommended approach and alternatives"