PMREMGenerator.js: Fix options field name in docstring

[ycw]

Related issue: -

Description

The 2nd options field should be position, not renderTarget

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	356.24 86.48	356.24 86.48	+0 B +0 B
WebGPU	615.49 172.75	615.49 172.75	+0 B +0 B
WebGPU Nodes	614.1 172.5	614.1 172.5	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	488.12 121.26	488.12 121.26	+0 B +0 B
WebGPU	685.04 188.04	685.04 188.04	+0 B +0 B
WebGPU Nodes	626.76 171.25	626.76 171.25	+0 B +0 B