Update "How to install Osmosis (Windows)" Troubleshooting section to use the correct shell variable

[achieveordie]

I found an outdated piece of documentation when I was following the Install Osmosis on Windows.

In the troubleshooting section, one of the ways recommended is by manually finding and setting the %JAVACMD% variable to point to the main Java directory. But as of osmosis version 0.49.2 I found that the variable has been changed to %JAVA_EXE% which should be manually overridden, an update in the documentation would be useful for the new users that are trying to install osmosis.