[spec] Add services overview section.

Signed-off-by: Miguel Osorio <[email protected]>

Author: moidx

docs/src/specification/services/README.md

@@ -1,5 +1,13 @@
 # Services
 
+The OpenPRoT services layer provides a standardized set of security and
+management functions that are essential for a Platform Root of Trust (PRoT).
+Built on top of the middleware and Hardware Abstraction Layer (HAL), this layer
+offers high-level capabilities that applications can leverage to ensure system
+integrity, security, and reliability.
+
+The following services are defined in the OpenPRoT specification:
+
 *   [Firmware Update](./fwupdate.md)
 *   [Attestation](./attestation.md)
 *   Firmware Recovery (TBD)