docs: migrate renderer examples to buffer macro and update docs

Update all documentation and code examples to use the new
`#[renderer(buffer)]`
pattern with `r_println!` instead of manually constructing
`RenderResult`
with `writeln!`.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/pages/14-testing.md b/docs/pages/14-testing.md
index fa196b0..65fedc9 100644
--- a/docs/pages/14-testing.md
+++ b/docs/pages/14-testing.md
@@ -16,7 +16,7 @@ Renderer is the easiest to test — call the function, assert the result:
 #[renderer]
 fn render_greet(result: ResultName) -> RenderResult {
     let mut r = RenderResult::new();
-    writeln!(r, "Hello, {}!", *result).ok();
+    r_println!(r, "Hello, {}!", *result);
     r
 }