Remove c# exprange info

[bbrainstormer]

PropertyHint.ExpRange was removed in godot 3.4. This commit removes the outdated information from the wiki.

[raulsntos]

PropertyHint.ExpRange was removed in godot 3.4

It hasn't been removed in 3.x, only in 4.x:

• Fix editor suffixes and degrees conversion godot#50009.

PROPERTY_HINT_EXP_RANGE was removed from Core in favor of PROPERTY_HINT_RANGE which can now do exponential ranges when including "exp" in the hint string.

The documentation has already been removed from the GDScript exports documentation:

• GDScript: Remove reference to @export_exp_range #5266.

This PR is correct for all versions of 4.x starting from 4.0.

[mhilbrunner]

Thanks and congrats on your first merged contribution to Godot's docs!

Note for future PRs: Its best practice to open PRs from a branch instead of your master branch :)