remove duplicate sso node under concepts

articles/active-directory/manage-apps/toc.yml

@@ -49,15 +49,15 @@
  items: 
  - name: What is single sign-on
  href: what-is-single-sign-on.md
- - name: Enabling SSO for your multi-tenant application 
+ - name: Enable SSO for your multi-tenant application 
  href: isv-sso-content.md
  - name: Create an Azure tenant for multi-tenant application
  href: isv-tenant-multi-tenant-app.md
  - name: Choose multi-tenant federation
  href: isv-choose-multi-tenant-federation.md
  - name: Create documentation for multi-tenant application
  href: isv-create-sso-documentation.md
- - name: Planning a single sign-on deployment
+ - name: Plan a single sign-on deployment
  href: plan-sso-deployment.md
  - name: One Click SSO
  items:
@@ -81,20 +81,6 @@
  href: tenant-restrictions.md
  - name: Configure SAML token encryption (Preview)
  href: howto-saml-token-encryption.md
- - name: Single sign-on
- items: 
- - name: What is single sign-on
- href: what-is-single-sign-on.md
- - name: Planning a single sign-on deployment
- href: plan-sso-deployment.md
- - name: Enable single Sign-on in your multi-tenant application
- href: isv-sso-content.md
- - name: Choose the right SSO federation protocol
- href: isv-choose-multi-tenant-federation.md
- - name: Create and Azure tenant for your multi-tenant application
- href: isv-tenant-multi-tenant-app.md
- - name: Create and publish SSO documentation for your application
- href: isv-create-sso-documentation.md
  - name: End-user portals
  href: end-user-experiences.md
  - name: How-to guides