Update psa_internal_storage.md

docs/api/storage/psa_internal_storage.md

@@ -1,20 +1,20 @@
-## PSA Internal Storage
+## PSA internal storage
 
-### Description
+PSA internal storage APIs enable saving data to and retrieving data from a PSA internal flash.
 
-PSA internal storage APIs allows saving and retrieving data from PSA internal flash.
+The implementation of PSA internal storage varies depending on the target type:
 
-PSA internal storage implementation varies depending on the target type:
-- on single core ARMv7-M target it PSA internal storage APIs are implemented by calling to "default" internal TDBStore instance.
-- on PSA targets implementing SPM, PSA internal storage implemented as a secure service. PSA internal storage has access control list, 
- which makes sure that only the entries created from NSPE will be accessible to it.
+* On a single core ARMv7-M target, PSA internal storage APIs are implemented by calling the default internal TDBStore instance.
+* On PSA targets that implement Secure Partition Manager (SPM), PSA internal storage is implemented as a secure service. The service uses an access control list to ensure that it only accesses entries created from the Non-Secure Processing Environment (NSPE).
 
-### Specification
+### PSA internal storage class reference
 
-API specification in mbed-os specific context can be found here: [mbed-os/Storage](../../storage/storage.md) 
+[![View code](https://www.mbed.com/embed/?type=library)](../mbed-os-api-doxy/psa__prot__internal__storage_8h.html)
 
-PSA specification can be found here [PSA Secure Storage](https://pages.arm.com/PSA-APIs)
+### Example
 
-### Doxygen
+### Related content
 
-[![View code](https://www.mbed.com/embed/?type=library)](../mbed-os-api-doxy/psa__prot__internal__storage_8h.html)
+* [Storage overview (Mbed OS)](..apis/storage.html).
+
+* [PSA secure storage](https://pages.arm.com/PSA-APIs).