Update README with manual download instructions

The readme file has been updated to include a 'Manual' section explaining how to download the latest release of 'cclip' library from the releases page. Additionally, an error in the usage code that referred to the wrong header file name has been fixed.

Author: Drew-Chase

README.md

@@ -11,8 +11,8 @@ git clone https://github.com/Drew-Chase/cclip.git ./vendor/cclip
 ```bash
 git submodule add https://github.com/Drew-Chase/cclip.git ./vendor/cclip
 ```
-
-
+### Manual
+Download the latest release from the [releases page](https://github.com/Drew-Chase/cclip/releases) and extract the options_manager.hpp to your project's directory.
 
 ## Usage
 
@@ -21,7 +21,7 @@ git submodule add https://github.com/Drew-Chase/cclip.git ./vendor/cclip
 Here is an example of how to use the `cclip` library to parse command-line arguments in a C++ program:
 
 ```cpp
-#include "cclip/options_manager.h"
+#include "cclip/options_manager.hpp"
 #include <iostream>
 
 int main(int argc, char **argv) {