[Docs] Fix a typo in Create Index naming limitation (#30891)

Author: lipsill

docs/reference/indices/create-index.asciidoc

@@ -23,7 +23,7 @@ There are several limitations to what you can name your index.  The complete lis
 - Cannot include `\`, `/`, `*`, `?`, `"`, `<`, `>`, `|`, ` ` (space character), `,`, `#`
 - Indices prior to 7.0 could contain a colon (`:`), but that's been deprecated and won't be supported in 7.0+
 - Cannot start with `-`, `_`, `+`
-- Cannot be `.` or ``..`
+- Cannot be `.` or `..`
 - Cannot be longer than 255 bytes (note it is bytes, so multi-byte characters will count towards the 255 limit faster)
 
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