Update Troubleshooting.md (#379)

fix #377

Troubleshooting.md

@@ -10,8 +10,8 @@ There are 2 types of command execution methods.
   
 ### Requirements
 
-* **Java**. Java Runtime is essential to run Maven commands.
-* **Maven / Maven Wrapper**. The extension actually leverages Maven executable file in your local machine. By default, it tries the following ones in order:
+* Install **Java**. Java Runtime is essential to run Maven commands. E.g. [AdoptOpenJDK](https://adoptopenjdk.net/), [Oracle OpenJDK](https://jdk.java.net/), etc.
+* **[Install Maven](https://maven.apache.org/install.html) / Maven Wrapper**. The extension actually leverages Maven executable file in your local machine. By default, it tries the following ones in order:
   1. The absolute path specified in config `maven.executable.path` if it is not empty.
   2. `mvnw` file under your workspace root folder. (If you prefer to bypass this one, you can change value of config `maven.executable.preferMavenWrapper` to `false`.)
   3. `mvn` in your system's `PATH`.
@@ -41,4 +41,4 @@ Error message can be collected either **directly from the integrated terminal**,
     This environment variable is needed to run this program
     NB: JAVA_HOME should point to a JDK not a JRE
     ```
-    In this case, please specify a correct `JAVA_HOME` environment variable, or re-install JRE/JDK if necessary.
+    In this case, please specify a correct `JAVA_HOME` environment variable, or re-install JRE/JDK if necessary.