Guide the meme caption step (#163)

ddiff --git a/server/views/index.js b/server/views/index.js
iindex fa8696e..24fec5b 100644
---- a/server/views/index.js
++++ b/server/views/index.js
@@@ -297,7 +297,7 @@ ${templates.map((t) => `<label class="mm-template${t.id === v.template_id ? ' is
  <label class="mm-field mm-ai-idea"><span>Get caption ideas</span><input name="idea_topic" type="text" maxlength="300" placeholder="what are you making a meme about?"><button class="mm-btn" type="button" data-caption-ideas>Make it with AI</button><small data-ai-status aria-live="polite">Available without signing in · cheapest OpenVibe.AI route by default</small></label>
  </fieldset>
  <label class="mm-field"><span>Who can see it?</span><select name="visibility"><option value="public"${v.visibility === 'public' ? ' selected' : ''}>Anyone</option><option value="unlisted"${v.visibility === 'unlisted' ? ' selected' : ''}>Anyone with the link</option><option value="hidden"${v.visibility === 'hidden' ? ' selected' : ''}>Only me</option></select></label>
--<div class="mm-actions"><button class="mm-btn" type="submit">Save the caption</button><button class="mm-btn mm-btn-quiet" type="submit" formaction="/make" formmethod="get">Preview</button></div>
++<div class="mm-actions"><button class="mm-btn" type="submit" data-ov-guide="meme.caption">Save the caption</button><button class="mm-btn mm-btn-quiet" type="submit" formaction="/make" formmethod="get">Preview</button></div>
  ${signedIn ? '' : '<p class="mm-fine">You can preview without signing in. <a href="/auth/login?next=%2Fmake">Sign in</a> to save a caption.</p>'}
  </form>
  <aside class="mm-preview" id="mm-preview" aria-labelledby="mm-preview-h"><h2 id="mm-preview-h">Your canvas</h2>
ddiff --git a/test/pages.test.js b/test/pages.test.js
iindex 6cb8c8b..8810896 100644
---- a/test/pages.test.js
++++ b/test/pages.test.js
@@@ -159,6 +159,7 @@ function jsonLd(html) {
              assert.strictEqual(form.headers.get('cache-control'), 'public, max-age=60');
              assert.ok(form.text.includes('id="mm-make"'));
              assert.ok(form.text.includes('id="mm-caption-form"'));
++            assert.ok(form.text.includes('data-ov-guide="meme.caption"'), 'the caption form has the Quest guide target');
              assert.ok(form.text.includes(`/img/template-`));
              const preview = await t.get(`/make?template_id=${tpl.id}&line1=when%20the%20robot&line2=is%20offline`);
              assert.strictEqual(preview.status, 200);