Suggested fix for Issue #37240 - Update documentation for the changes I needed...

Suggested fix for Issue #37240 - Update documentation for the changes I needed to install Java using the scripts (#37241)

* Update BuildFromSource.md

When following these steps, I noticed an error installing the JDK in the repo using the included script, so I had to follow these additional instructions to get past that.

Source for the instructions : https://stackoverflow.com/questions/4037939/powershell-says-execution-of-scripts-is-disabled-on-this-system

* Update BuildFromSource.md

Additional step to temporarily set environmental variable

* Update BuildFromSource.md

Wrong markdown