Update documentation section "#guice-dependency-injection"

[ehayik]

TestNG Version

7.1.1

Version 7.1.1 allow users to provide DI Injector and how to do it is described in issue #2200 However it isn't described in TestNG documentation

[krmahadevan]

@eljaiek - It looks like the injection mechanism still doesn't work with surefire plugin.

The PR #2207 aims at fixing that. So once that is done and the fix released, I thought it would be more apt to have the documentation updated to reflect this information.

[cvagnathan]

@krmahadevan @ehayik
Looks like #2207 was fixed and merged.
Would like to understand, pick this task and contribute.

[krmahadevan]

@cvagnathan - Sure thing.. Please go ahead.