updated many_glyphs description

examples/stress_tests/many_glyphs.rs

@@ -1,6 +1,6 @@
 //! Simple text rendering benchmark.
 //!
-//! Creates a `Text` with a single `TextSection` containing `100_000` glyphs,
+//! Creates a text block with a single span containing `100_000` glyphs,
 //! and renders it with the UI in a white color and with Text2d in a red color.
 //!
 //! To recompute all text each frame run