SAML: add <mdui:UIInfo> element examples (#8718)

add some mdui:UIInfo element examples for saml2_config in homeserver.yaml

changelog.d/8718.misc

@@ -0,0 +1 @@
+Add some `mdui:UIInfo` element examples for `saml2_config` in the homeserver config.

docs/sample_config.yaml

@@ -1560,6 +1560,28 @@ saml2_config:
     #description: ["My awesome SP", "en"]
     #name: ["Test SP", "en"]
 
+    #ui_info:
+    #  display_name:
+    #    - lang: en
+    #      text: "Display Name is the descriptive name of your service."
+    #  description:
+    #    - lang: en
+    #      text: "Description should be a short paragraph explaining the purpose of the service."
+    #  information_url:
+    #    - lang: en
+    #      text: "https://example.com/terms-of-service"
+    #  privacy_statement_url:
+    #    - lang: en
+    #      text: "https://example.com/privacy-policy"
+    #  keywords:
+    #    - lang: en
+    #      text: ["Matrix", "Element"]
+    #  logo:
+    #    - lang: en
+    #      text: "https://example.com/logo.svg"
+    #      width: "200"
+    #      height: "80"
+
     #organization:
     #  name: Example com
     #  display_name:

synapse/config/saml2_config.py

@@ -271,6 +271,28 @@ def generate_config_section(self, config_dir_path, server_name, **kwargs):
             #description: ["My awesome SP", "en"]
             #name: ["Test SP", "en"]
 
+            #ui_info:
+            #  display_name:
+            #    - lang: en
+            #      text: "Display Name is the descriptive name of your service."
+            #  description:
+            #    - lang: en
+            #      text: "Description should be a short paragraph explaining the purpose of the service."
+            #  information_url:
+            #    - lang: en
+            #      text: "https://example.com/terms-of-service"
+            #  privacy_statement_url:
+            #    - lang: en
+            #      text: "https://example.com/privacy-policy"
+            #  keywords:
+            #    - lang: en
+            #      text: ["Matrix", "Element"]
+            #  logo:
+            #    - lang: en
+            #      text: "https://example.com/logo.svg"
+            #      width: "200"
+            #      height: "80"
+
             #organization:
             #  name: Example com
             #  display_name: