changelog: fix text and typos

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/ChangeLog.d/8709.txt b/ChangeLog.d/8709.txt
index a95cedf..8c15797 100644
--- a/ChangeLog.d/8709.txt
+++ b/ChangeLog.d/8709.txt
@@ -1,5 +1,5 @@
 Features
-   * The new function mbedtls_pk_copy_from_psa() provides a way to setup
-     a PK context starting from a PSA key. In contrast to
-     mbedtls_pk_setup_opaque() the resulting PK context is a normal context
-     that's independent from the original PSA key.
+   * The new function mbedtls_pk_copy_from_psa() provides a way to set up
+     a PK context starting from a PSA key. The new function
+     mbedtls_pk_copy_from_psa() provides a way to set up a PK context with the
+     same content as a PSA key.