docs(seo): clarify alt vs caption in pre-publish checklist

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/generator/generator.py

@@ -284,8 +284,8 @@ def _seo_checklist(slug: str) -> str:
     be all-fail noise. Jose runs `seo-check <slug>` after filling these in."""
     return (
         "\n\n⚠️ Antes de publicar, añade: meta title, meta description (≤145), "
-        "custom excerpt, OG/Twitter, feature image + alt, 2-3 internal links "
-        "(donde sea natural)\n"
+        "custom excerpt, OG/Twitter, feature image + alt (campo Alt, NO Caption), "
+        "2-3 internal links (donde sea natural)\n"
         f"Luego valida:  seo-check {slug}"
     )
 
@@ -312,7 +312,7 @@ def _seo_checklist_slim(slug: str) -> str:
     """Slimmed checklist for the autofill path: meta/OG/excerpt/tags/links are
     already on the draft, so only the human-only bits remain."""
     return (
-        "⚠️ Antes de publicar: añade *feature image + alt*, luego:\n"
+        "⚠️ Antes de publicar: añade *feature image + alt* (campo Alt, NO Caption), luego:\n"
         f"`seo-check {slug}`"
     )