fix(templates): Bug issue template should use placeholder

The bug issue template used `value` instead of `placeholder` for certain fields, leading to issue reports like #1012. This commit fixes that.

Author: BYK

.github/ISSUE_TEMPLATE/bug.yml

@@ -14,7 +14,7 @@ body:
     attributes:
       label: Steps to Reproduce
       description: How can we see what you're seeing? Specific is terrific.
-      value: |-
+      placeholder: |-
         1. foo
         2. bar
         3. baz
@@ -31,7 +31,7 @@ body:
     attributes:
       label: Actual Result
       description: Logs? Screenshots? Yes, please.
-      value: |-
+      placeholder: |-
         e.g.:
         - latest install logs: `ls -1 sentry_install_log-*.txt | tail -1 | xargs cat`
         - `docker-compose logs` output