Wording of "Vampire Numbers" (code-golf#457)

* Capitalized proper nouns

Capitalized "Arabic", "Roman" and "Unicode"

* Wording of "Vampire Numbers"

Proposed improvement as per the Discord discussion on March 4th

holes.toml

@@ -1893,8 +1893,8 @@ preamble = '''
 <p>
     A vampire number is a non-negative number that can be factored into two
     numbers (fangs) each with half as many digits as the original where the
-    two factors contain all the digits of the original, in any order. Both
-    fangs may not have trailing zeros.
+    two factors contain all the digits of the original, in any order. One but
+    not both fangs may have trailing zeros.
 
 <p>
     For example <b>1260 = 21*60</b>, <b>1395 = 15*93</b>, <b>1435 = 35*41</b>,