refactor: changed type of field of ShellOption

FossilOrigin-Name: 9279591baf0d8458e3f96d1cbeb03ec5e943fb49cc72ea86ebc91e9255ec9c58

Author: thindil

src/help.nim

@@ -212,7 +212,7 @@ proc showHelp(topic: UserInput; db): ResultCode {.sideEffect, raises: [
         showOutput(message = "\n", newLine = false, db = db)
 
     type ShellOption = ref object
-      value: string = ""
+      value: OptionValue = ""
 
     proc showHelpList(keys: seq[ShellOption];
         withNumbers: bool = true) {.sideEffect, raises: [], tags: [