KEP-3027: Add one line motivation and update TOC

Signed-off-by: Adolfo García Veytia (Puerco) <[email protected]>

Author: puerco

keps/sig-release/3027-slsa-compliance/README.md

@@ -97,6 +97,7 @@ tags, and then generate with `hack/update-toc.sh`.
     - [SLSA Level 2: Tamper Resistance of the Build Service](#slsa-level-2-tamper-resistance-of-the-build-service)
     - [SLSA Level 3: Extra Resistance to Specific Threats](#slsa-level-3-extra-resistance-to-specific-threats)
     - [SLSA Level 4: Highest Levels of Confidence and Trust](#slsa-level-4-highest-levels-of-confidence-and-trust)
+- [Implementation History](#implementation-history)
 <!-- /toc -->
 
 ## Release Signoff Checklist
@@ -151,8 +152,8 @@ is a framework to harden software supply currently being defined by the
 Group](https://github.com/ossf/wg-digital-identity-attestation).
 
 The framework provides requirements and recommendations to software
-build systems to harden the environments and processes that drive them.
-It also defines the metadata that needs to be produced to trace the 
+build systems to harden their environments and the processes that drive
+them. It also defines the metadata that needs to be produced to trace the 
 origins of every item in a software release.
 
 The main goal of this enhancement is to provide downstream consumers of our
@@ -184,6 +185,8 @@ updates.
 
 ## Motivation
 
+Release Kubernetes in a zero-trust environment.
+
 Kubernetes releases represent key links in many software supply chains, not
 just for the project itself but also for consumers that derive, repackage and
 distribute our artifacts downstream. The project releases end-user artifacts