Fixing broken links

docs/content/concepts/layer/control/_index.md

@@ -11,6 +11,7 @@ toc:
 aliases:
   - /documentation/schema/catalog-layer/
   - /documentation/schema/profile-layer/
+  - /concepts/layer/control/mapping
 ---
 
 The OSCAL control layer consists of the following models.
@@ -23,6 +24,10 @@ It is important to note that the OSCAL catalog model is not a catalog document f
 
 Controls must also be encoded in a standard machine-readable form. The OSCAL model gives the designers of catalogs great flexibility in the details of how controls are defined, with their constituent parts. This is described further in a page providing a high-level introductory walkthrough of an [Annotated Example](catalog/sp800-53rev5-example) of a control, as defined by NIST SP 800-53 Revision 5.
 
+## Mapping Model
+
+The **[Mapping Model](mapping/)** provides a means to represent control mappings between two catalogs using a structured, machine-readable representation. The OSCAL mapping model can be represented in XML, JSON, and YAML formats.
+
 ## Profile Model
 
 The **[Profile Model](profile/)** provides a structured, machine-readable representation of a **[baseline](../../terminology/#baseline)**. As the starting point for defining an organization's security mission and security posture, a baseline must be defined by any organization undertaking a risk-based security program or security assessment, typically by selecting and adapting controls from an authoritative catalog of controls, or from another baseline that has already been defined and described.

docs/content/learn/tutorials/general/extension.md

@@ -595,7 +595,7 @@ Line 11 demonstrates the use of `<link>` to point to the organization's official
           "text": "HSPD-12"
         },
         {
-          "href": "http://federal-agency.gov/img/official-agency-logo.png",
+          "href": "https://federal-agency.gov/img/official-agency-logo.png",
           "rel": "logo",
           "media-type": "image/png"
         }