docs(library): add json schema spec links

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: baywet

src/Microsoft.OpenApi/Models/Interfaces/IOpenApiSchemaMissingProperties.cs

@@ -14,6 +14,7 @@ public interface IOpenApiSchemaMissingProperties
 {
     /// <summary>
     /// $anchor - identifies a plain-name location-independent fragment within the schema resource.
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-anchor
     /// </summary>
     public string? Anchor { get; }
 
@@ -45,41 +46,49 @@ public interface IOpenApiSchemaMissingProperties
     public IOpenApiSchema? UnevaluatedPropertiesSchema { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-validation#name-contentencoding
     /// contentEncoding - identifies the encoding of string content.
     /// </summary>
     public string? ContentEncoding { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-validation#name-contentmediatype
     /// contentMediaType - identifies the media type of string content.
     /// </summary>
     public string? ContentMediaType { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-validation#name-contentschema
     /// contentSchema - provides a schema that describes the decoded string content.
     /// </summary>
     public IOpenApiSchema? ContentSchema { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-propertynames
     /// propertyNames - provides a schema that validates property names.
     /// </summary>
     public IOpenApiSchema? PropertyNames { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-dependentschemas
     /// dependentSchemas - maps property names to schemas that are applied when that property is present.
     /// </summary>
     public IDictionary<string, IOpenApiSchema>? DependentSchemas { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-if
     /// if - applies a conditional schema that determines whether <see cref="Then"/> or <see cref="Else"/> should be evaluated.
     /// </summary>
     public IOpenApiSchema? If { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-then
     /// then - applies when <see cref="If"/> evaluates successfully.
     /// </summary>
     public IOpenApiSchema? Then { get; }
 
     /// <summary>
+    /// Follow JSON Schema definition: https://json-schema.org/draft/2020-12/json-schema-core#name-else
     /// else - applies when <see cref="If"/> does not evaluate successfully.
     /// </summary>
     public IOpenApiSchema? Else { get; }