Document default prefix/suffix values

Closes gh-10290

spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -230,6 +230,22 @@
       "http://localhost:9200"
     ]
   },
+  {
+    "name": "spring.freemarker.prefix",
+    "defaultValue": ""
+  },
+  {
+    "name": "spring.freemarker.suffix",
+    "defaultValue": ".ftl"
+  },
+  {
+    "name": "spring.groovy.template.prefix",
+    "defaultValue": ""
+  },
+  {
+    "name": "spring.groovy.template.suffix",
+    "defaultValue": ".tpl"
+  },
   {
     "name": "spring.http.encoding.enabled",
     "type": "java.lang.Boolean",
@@ -399,6 +415,14 @@
     "description": "Enable SitePreferenceHandler.",
     "defaultValue": true
   },
+  {
+    "name": "spring.mustache.prefix",
+    "defaultValue": "classpath:/templates/"
+  },
+  {
+    "name": "spring.mustache.suffix",
+    "defaultValue": ".html"
+  },
   {
     "name": "spring.mvc.favicon.enabled",
     "type": "java.lang.Boolean",
@@ -504,6 +528,14 @@
     "type": "java.lang.Boolean",
     "description": "Enable the connection status view for supported providers.",
     "defaultValue": false
+  },
+  {
+    "name": "spring.thymeleaf.prefix",
+    "defaultValue": "classpath:/templates/"
+  },
+  {
+    "name": "spring.thymeleaf.suffix",
+    "defaultValue": ".html"
   }
 ],"hints": [
   {

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -250,7 +250,7 @@ content into your application; rather pick only the properties that you need.
 	spring.freemarker.prefix= # Prefix that gets prepended to view names when building a URL.
 	spring.freemarker.request-context-attribute= # Name of the RequestContext attribute for all views.
 	spring.freemarker.settings.*= # Well-known FreeMarker keys which will be passed to FreeMarker's Configuration.
-	spring.freemarker.suffix= # Suffix that gets appended to view names when building a URL.
+	spring.freemarker.suffix=.ftl # Suffix that gets appended to view names when building a URL.
 	spring.freemarker.template-loader-path=classpath:/templates/ # Comma-separated list of template paths.
 	spring.freemarker.view-names= # White list of view names that can be resolved.