RelNotes: improve wording of credential helper notes

Offer a slightly more verbose description of the issue fixed by
7144dee (credential/libsecret: erase matching creds only, 2023-07-26)
and cb626f8 (credential/wincred: erase matching creds only,
2023-07-26).

Signed-off-by: Todd Zullinger <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: tmzullinger

Documentation/RelNotes/2.43.0.txt

@@ -37,8 +37,9 @@ UI, Workflows & Features
    oath token and password expiration data) are stored in libsecret
    keyrings has been rethought.
 
- * Update two credential helpers to correctly match which credential
-   to erase; they dropped not the ones with stale password.
+ * Update the libsecret and wincred credential helpers to correctly
+   match which credential to erase; they erased the wrong entry in
+   some cases.
 
  * Git GUI updates.