Polishing.

Fix typo in reference docs.

See #3758

Author: mp911de

src/main/asciidoc/reference/aggregation-framework.adoc

@@ -88,7 +88,7 @@ At the time of this writing, we provide support for the following Aggregation Op
 | `abs`, `add` (+++*+++ via `plus`), `ceil`, `divide`, `exp`, `floor`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `round`, `sqrt`, `subtract` (+++*+++ via `minus`), `trunc`
 
 | String Aggregation Operators
-| `concat`, `substr`, `toLower`, `toUpper`, `stcasecmp`, `indexOfBytes`, `indexOfCP`, `split`, `strLenBytes`, `strLenCP`, `substrCP`, `trim`, `ltrim`, `rtim`
+| `concat`, `substr`, `toLower`, `toUpper`, `strcasecmp`, `indexOfBytes`, `indexOfCP`, `split`, `strLenBytes`, `strLenCP`, `substrCP`, `trim`, `ltrim`, `rtim`
 
 | Comparison Aggregation Operators
 | `eq` (+++*+++ via `is`), `gt`, `gte`, `lt`, `lte`, `ne`