Tweak SSRL performance cost in 3D antialiasing comparison table

[Calinou]

• Follow-up to Add Antialiasing comparison table, remove redundant MSAA limitations section #10167.

The screen-space roughness limiter's performance cost is very low compared to other antialiasing methods (typically in the same ballpark as FXAA).

[clayjohn]

That's right. I would say even lower than FXAA

[tetrapod00]

Thanks. The current SSRL body text also calls the cost "small", so the table now matches the current description.

(The cost was called "moderate" in the removed MSAA limitations section, so I probably used that as the source for "medium cost" instead of the more up-to-date info in the AA page itself)

[mhilbrunner]

Thanks!