Refactored readme's requirements
Refactored readme's requirements

Added a server compatibility table

PhilippRo/vscode-janus-debug,PhilippRo/vscode-janus-debug,bkircher/vscode-janus-debug,tineheller/vscode-janus-debug,otris/vscode-janus-debug,otris/vscode-janus-debug,bkircher/vscode-janus-debug,tineheller/vscode-janus-debug