add Objective-C++ documentations for c/cpp section

.vitepress/config.ts

@@ -255,6 +255,7 @@ export default defineConfig({
               ],
             },
             { text: 'Objective-C', link: '/cpp/objective-c' },
+            { text: 'Objective-C++', link: '/cpp/objective-cpp' },
           ],
         },
         {

src/cpp/objective-cpp.md

@@ -0,0 +1,58 @@
+# Objective-C++
+
+Objective-C++ implements Objective-C's plugins for C++. In this way, it becomes possible to use Objective-C elements with C++ codes. With Jule, you can use Objective-C++ like Objective-C.
+
+## Using
+
+You can create your header files with the extension `.h` in the standard way. But we recommended o use `.hpp` extension for C++ headers. These are does not pose any compatibility issues as it is one of the standard extensions supported by Jule.
+
+For recommended development experience, declarations should be in the header file and implementation in another source code file. In this context, let's say we have Objective-C++ code like this:
+
+Our `log.hpp`:
+```objective-cpp
+#ifndef LOG_HPP
+#define LOG_HPP
+
+void Log(const char *text);
+
+#endif // LOG_HPP
+```
+
+Our `log.mm`:
+```objective-cpp
+#include "log.hpp"
+
+#include <Foundation/Foundation.h>
+
+void Log(const char *text) {
+    NSString *log = [[NSString alloc] initWithUTF8String:text];
+    NSLog(@"%@", log);
+}
+```
+
+We want to use above Objective-C++ code with Jule. The first thing we need to do is pass the `-framework Foundation` argument to the build command using the `jule:pass` top-directive. Otherwise, we will encounter a compilation error.
+
+Then we link the definitions we want to use by linking the relevant header file and source code. Then we are ready to use it.
+
+Our `main.jule`:
+```jule
+//jule:pass -framework Foundation
+
+cpp use "log.hpp"
+cpp use "log.mm"
+
+cpp type char: byte
+cpp unsafe fn Log(text: *cpp.char)
+
+fn Log(text: str) {
+    unsafe { cpp.Log((*cpp.char)(&text[0])) }
+}
+
+fn main() {
+    Log("Log from Jule!")
+}
+```
+
+::: tip
+The above code also has wrapper in a Jule for linked function. This increases safety and makes it easier to maintain the relevant function.
+:::