docs(challenge-06): clarify PR titles are scoped to a single challenge (#253)

support#64 (DebeeArmstrong): Challenge 6 tells students to write any
descriptive PR title, but Challenge 7's automatically-opened practice
PR has a fixed title chosen by the automation. Nothing said these are
unrelated, so a reader could think a specific title carries across
challenges. Add a one-line note that titles only apply to that PR and
some later challenges (like 7) open their own separate, auto-titled PR.

Co-authored-by: GitHub Workshop Bot <workshop@example.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: 3 people

docs/06-working-with-pull-requests.md

@@ -137,6 +137,8 @@ This is your first challenge that uses GitHub's web editor, so take a moment wit
 3. Verify the **base branch** is `main` and the **compare branch** is your `fix/yourname-issueXX` branch.
 4. Activate the **Create pull request** button.
 
+> **Note:** This title only needs to make sense for this one PR. It has no bearing on later chapters - some later challenges (Chapter 7, for example) automatically open their own separate pull request with a title the automation chooses. You never need to reuse or match a title across challenges.
+
 **You are done when:** Your PR appears in the Pull Requests list. The bot will begin running checks within about 30 seconds. Continue to Challenge 6.3.
 
 ### Challenge 6.3 Step-by-Step: Pass Required Checks

html/docs/06-working-with-pull-requests.html

@@ -457,6 +457,9 @@ <h3 id="challenge-62-step-by-step-open-a-linked-pr">Challenge 6.2 Step-by-Step:
 <li>Verify the <strong>base branch</strong> is <code>main</code> and the <strong>compare branch</strong> is your <code>fix/yourname-issueXX</code> branch.</li>
 <li>Activate the <strong>Create pull request</strong> button.</li>
 </ol>
+<blockquote>
+<p><strong>Note:</strong> This title only needs to make sense for this one PR. It has no bearing on later chapters - some later challenges (Chapter 7, for example) automatically open their own separate pull request with a title the automation chooses. You never need to reuse or match a title across challenges.</p>
+</blockquote>
 <p><strong>You are done when:</strong> Your PR appears in the Pull Requests list. The bot will begin running checks within about 30 seconds. Continue to Challenge 6.3.</p>
 <h3 id="challenge-63-step-by-step-pass-required-checks">Challenge 6.3 Step-by-Step: Pass Required Checks</h3>
 <p><strong>Goal:</strong> Read bot feedback, fix any issues it finds, and get all required checks to pass.</p>