fix docs

Author: puredanger

content/reference/clojure_cli.adoc

@@ -892,8 +892,8 @@ Some tools provide functions designed to be used for programmatic execution from
 There are several argument map keys that have special significance to the Clojure CLI during -X or -T. All of these keys will be removed from the argument map before the function is invoked:
 
 * `:clojure.exec/invoke` - `true` to use this protocol
-* `:clojure.exec/out` - `true` to capture and return stdout during function execution
-* `:clojure.exec/err` - `true` to capture and return stderr during function execution
+* `:clojure.exec/out` - `:capture` to capture and return stdout during function execution
+* `:clojure.exec/err` - `:capture` to capture and return stderr during function execution
 
 The result is wrapped into a printed envelope map with the following keys and returned via the CLI stdout: