Link to function catalog docs for config props (#526)

Prior to this commit, each app documented its available config props
in its README.adoc. Now that the functions have been moved to the
function catalog, these inline docs are replaced w/ a link to the
respective function catalog docs.

See #524

applications/source/xmpp-source/README.adoc

@@ -17,25 +17,8 @@ N/A
 
 The **$$xmpp$$** $$source$$ has the following options:
 
-//tag::configuration-properties[]
-Properties grouped by prefix:
-
-
-=== xmpp.factory
-
-$$host$$:: $$XMPP Host server to connect to.$$ *($$String$$, default: `$$<none>$$`)*
-$$password$$:: $$The Password for the connected user.$$ *($$String$$, default: `$$<none>$$`)*
-$$port$$:: $$Port for connecting to the host. - Default Client Port: 5222$$ *($$Integer$$, default: `$$5222$$`)*
-$$resource$$:: $$The Resource to bind to on the XMPP Host. - Can be empty, server will generate one if not set$$ *($$String$$, default: `$$<none>$$`)*
-$$security-mode$$:: $$<documentation missing>$$ *($$SecurityMode$$, default: `$$<none>$$`, possible values: `required`,`ifpossible`,`disabled`)*
-$$service-name$$:: $$The Service Name to set for the XMPP Domain.$$ *($$String$$, default: `$$<none>$$`)*
-$$subscription-mode$$:: $$<documentation missing>$$ *($$SubscriptionMode$$, default: `$$<none>$$`, possible values: `accept_all`,`reject_all`,`manual`)*
-$$user$$:: $$The User the connection should connect as.$$ *($$String$$, default: `$$<none>$$`)*
-
-=== xmpp.supplier
-
-$$payload-expression$$:: $$<documentation missing>$$ *($$Expression$$, default: `$$<none>$$`)*
-$$stanza-filter$$:: $$<documentation missing>$$ *($$StanzaFilter$$, default: `$$<none>$$`)*
+//tag::configuration-properties[link-to-catalog=true]
+https://github.com/spring-cloud/spring-functions-catalog/tree/main/supplier/spring-xmpp-supplier#configuration-options[See Spring Functions Catalog for configuration options].
 //end::configuration-properties[]
 
 Also see the https://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html[Spring Boot Documentation]