remove the "Adding plug-in parameters to .che/che-theia-plugins.yaml" section in User guide

Chapter 10 of the User Guide [1] and especially section 10.3 [2] reference the Theia editor. Please ensure the docs (including these sections) change to reflect use of the VSCode editor when the default editor changes. (Believed to be in release 3.3).

Thank you!

[1] https://access.redhat.com/documentation/en-us/red_hat_openshift_dev_spaces/3.2/html/user_guide/adding-visual-studio-code-extension#doc-wrapper
[2] https://access.redhat.com/documentation/en-us/red_hat_openshift_dev_spaces/3.2/html/user_guide/adding-visual-studio-code-extension#che-theia-plug-ins-YAML