Add Self Assessments as a subproject to SIG Security (#7221)

* Update sigs.yaml

Adding Self Assessments as a subproject to SIG Security

* run make

sig-security/README.md

@@ -38,6 +38,12 @@ The Chairs of the SIG run operations and processes governing the SIG.
 ## Subprojects
 
 The following [subprojects][subproject-definition] are owned by sig-security:
+### security-assessments
+Security self assessments for upstream projects
+- **Owners:**
+  - [kubernetes/sig-security/sig-security-assessments](https://github.com/kubernetes/sig-security/blob/main/sig-security-assessments/OWNERS)
+- **Contact:**
+  - Slack: [#sig-security-assessments](https://kubernetes.slack.com/messages/sig-security-assessments)
 ### security-audit
 Third Party Security Audit
 - **Owners:**

sigs.yaml

@@ -2556,6 +2556,12 @@ sigs:
       github: cpanato
       name: Carlos Tadeu Panato Jr.
   subprojects:
+  - name: security-assessments
+    description: Security self assessments for upstream projects
+    contact:
+      slack: sig-security-assessments
+    owners:
+    - https://raw.githubusercontent.com/kubernetes/sig-security/main/sig-security-assessments/OWNERS
   - name: security-audit
     description: Third Party Security Audit
     owners: