add documentation for mongodb backend

docs/modules/ROOT/nav.adoc

@@ -15,6 +15,7 @@
 *** xref:server/environment-repository/aws-parameter-store-backend.adoc[]
 *** xref:server/environment-repository/aws-secrets-manager-backend.adoc[]
 *** xref:server/environment-repository/credhub-backend.adoc[]
+*** xref:server/environment-repository/mongo-backend.adoc[]
 *** xref:server/environment-repository/composite-repositories.adoc[]
 *** xref:server/environment-repository/property-overrides.adoc[]
 *** xref:server/environment-repository/using-bootstrap-to-override-properties.adoc[]

docs/modules/ROOT/pages/server/environment-repository/mongo-backend.adoc

@@ -0,0 +1,56 @@
+[[mongo-backend]]
+= MongoDB Backend
+:page-section-summary-toc: 1
+
+Spring Cloud Config Server supports MongoDB as a backend for configuration properties.
+You can enable this feature by adding `spring-boot-starter-data-mongodb` to the classpath and using the `mongodb` profile.
+
+[source,xml,indent=0]
+.pom.xml
+----
+ <dependencies>
+ <dependency>
+ <groupId>org.springframework.boot</groupId>
+ <artifactId>spring-boot-starter-data-mongodb</artifactId>
+ </dependency>
+ </dependencies>
+----
+
+Configure your application's `application.properties` or `application.yml` to point to your MongoDB instance:
+
+[source,yaml]
+----
+spring:
+ data:
+ mongodb:
+ database: your-database-name
+ port: '27017'
+ host: localhost
+----
+
+The configuration properties should be stored in documents within the `properties` collection. Each document represents a set of properties for a given application, profile, and label.
+
+Example MongoDB document:
+
+[source,json]
+----
+{
+ "application": "myapp",
+ "profile": "development",
+ "label": "master",
+ "properties": {
+ "property1": "value1",
+ "property2": "value2"
+ }
+}
+----
+
+You can disable autoconfiguration for `MongoDbEnvironmentRepository` by setting the `spring.cloud.config.server.mongodb.enabled` property to `false`.
+
+The default values for MongoDB backend configuration are as follows:
+
+- **Collection Name:** `"properties"` (Name of the MongoDB collection to query for configuration properties.)
+
+- **Default Label:** `"master"` (Default label to use if none is specified.)
+
+NOTE: You can change these defaults by setting `spring.cloud.config.server.mongodb.collection` and `spring.cloud.config.server.mongodb.defaultLabel` in your application's configuration.