Update docs/topics/proc_running-the-containerless-mta-cli.adoc

Author: mpershina

docs/topics/proc_running-the-containerless-mta-cli.adoc

@@ -20,6 +20,10 @@ In {ProductShortName} 7.2.0 and later, containerless CLI is a default mode. To e
 
 * You have OpenJDK version 17 or later installed on your system.
 * You have Maven installed on your system.
+* The CLI assumes that a path to the `mvn` binary is correctly registered in the system variable. Therefore, ensure that you added `mvn` to the following variable:
++
+** `Path` for Windows.
+** `PATH` for Linux and macOS.
 * You have the `python3` package installed on your system.
 * You have the `JAVA_HOME` environmental variable set.
 * You have the `JVM_MAX_MEM` system variable set.