manual: More capitalization

* doc/org-manual.org (Verse blocks in LaTeX export): This is
a follow-up to last commit.

doc/org-manual.org

@@ -13901,7 +13901,7 @@ A complete example with Shakespeare's first sonnet:
 #+begin_src org
 ,#+ATTR_LATEX: :center t :latexcode \color{red} :lines 5
 ,#+ATTR_LATEX: :versewidth Feed’st thy light’st flame with self-substantial fuel,
-,#+begin_verse
+,#+BEGIN_VERSE
 From fairest creatures we desire increase,
 That thereby beauty’s rose might never die,
 But as the riper should by time decrease,
@@ -13916,7 +13916,7 @@ Within thine own bud buriest thy content
 And, tender churl, makest waste in niggarding.
 Pity the world, or else this glutton be,
 To eat the world’s due, by the grave and thee.
-,#+end_verse
+,#+END_VERSE
 #+end_src
 
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