doc: update opengl example

include/README.md

@@ -33,15 +33,9 @@ libra_gl_filter_chain_t load_gl_filter_chain(libra_gl_loader_t opengl, const cha
     std::cout << "Could not load preset\n";
     return NULL;
   }
-
-  // OpenGL runtime needs to be initialized.
-  if (librashader.gl_init_context(opengl) != NULL) {
-    std::cout << "Could not initialize OpenGL context\n";
-    return NULL;
-  }
   
   libra_gl_filter_chain_t chain;
-  if (librashader.gl_filter_chain_create(&preset, NULL, &chain) {
+  if (librashader.gl_filter_chain_create(&preset, opengl, NULL, &chain) {
     std::cout << "Could not create OpenGL filter chain\n";
   }
   return chain;

librashader-capi/src/runtime/gl/filter_chain.rs

@@ -305,6 +305,7 @@ extern_fn! {
     /// The resulting value in `chain` then becomes null.
     /// ## Safety
     /// - `chain` must be either null or a valid and aligned pointer to an initialized `libra_gl_filter_chain_t`.
+    /// - The context that the filter chain was initialized with **must be current** before freeing the filter chain.
     fn libra_gl_filter_chain_free(
         chain: *mut libra_gl_filter_chain_t
     ) {

librashader/src/lib.rs

@@ -259,9 +259,6 @@ pub mod runtime {
     /// Shader runtime for OpenGL 3.3+.
     ///
     /// DSA support requires OpenGL 4.6.
-    ///
-    /// The OpenGL runtime requires `gl` to be
-    /// initialized with [`gl::load_with`](https://docs.rs/gl/0.14.0/gl/fn.load_with.html).
     pub mod gl {
         pub use librashader_runtime_gl::{
             error,