Tweak wording in the bug report issue form

Author: pradyunsg

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -37,7 +37,7 @@ body:
     attributes:
       label: How to Reproduce
       description: Please provide steps to reproduce this bug.
-      value: |
+      placeholder: |
         1. Get package from '...'
         2. Then run '...'
         3. An error occurs.
@@ -49,7 +49,8 @@ body:
       label: Output
       description: >-
         Provide the output of the steps above, including the commands
-        themselves and pip's output/traceback etc.
+        themselves and pip's output/traceback etc. If you're familiar with
+        Markdown, this block will be rendered as a code block.
       render: sh-session
 
   - type: checkboxes