Document the CLI

Adds CLI usage documentation to the README covering installation via
SDKMAN, the apply and check commands, and available options.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: timothysparg

README.adoc

@@ -211,6 +211,53 @@ springJavaFormat {
 
 
 
+=== CLI
+The CLI provides formatting and checking support without requiring Maven or Gradle integration.
+
+WARNING: The CLI is experimental and not yet considered a stable interface.
+
+==== Download
+Native binaries for Linux, Windows, and macOS are published as assets on the corresponding https://github.com/spring-io/spring-javaformat/releases[GitHub release].
+
+==== Usage
+[source,shell]
+----
+spring-javaformat --help
+----
+
+The CLI provides the following commands:
+
+* `apply` formats Java source files in place
+* `validate` checks formatting without modifying files
+* `check` runs Spring style checks
+
+==== Examples
+Format sources in the current project:
+
+[source,shell]
+----
+spring-javaformat apply .
+----
+
+Validate formatting:
+
+[source,shell]
+----
+spring-javaformat validate .
+----
+
+Run style checks:
+
+[source,shell]
+----
+spring-javaformat check .
+----
+
+==== Configuration
+The `apply` and `validate` commands honor `.springjavaformatconfig`.
+
+
+
 === Java 8 Support
 By default, the formatter requires Java 17.
 If you are working on an older project, you can use a variation of the formatter based off Eclipse 2021-03 (the latest Eclipse JDT version built with Java 8).