Add new limit option to limit the requested amount of posts from the Reddit API (#203)

- Add the limit option
- Valid number between 1 and 100
- Defaults to 100
- Updated documentation to mention this

#137

Reviewed-on: #203
Reviewed-by: VylpesTester <tester@vylpes.com>
Co-authored-by: Ethan Lane <ethan@vylpes.com>
Co-committed-by: Ethan Lane <ethan@vylpes.com>

src/constants/ErrorCode.ts

@@ -3,4 +3,5 @@ export enum ErrorCode {
     FailedToFetchReddit,
     UnableToParseJSON,
     NoImageResultsFound,
+    LimitOutOfRange,
 }

src/constants/ErrorMessages.ts

@@ -2,4 +2,5 @@ export default class ErrorMessages {
     public static readonly FailedToFetchReddit = "Failed to fetch result from Reddit";
     public static readonly UnableToParseJSON = "Unable to parse the JSON result";
     public static readonly NoImageResultsFound = "No image results found in response from Reddit";
+    public static readonly LimitOutOfRange = "Limit must be a number between 1 and 100";
 }