Inline prepare() vs layout() tip in README

Co-Authored-By: no1x <no1ex.es@gmail.com>

Author: chenglou

README.md

@@ -28,9 +28,9 @@ const prepared = prepare('AGI 春天到了. بدأت الرحلة 🚀', '16px I
 const { height, lineCount } = layout(prepared, textWidth, 20) // pure arithmetics. No DOM layout & reflow!
 ```
 
-`prepare()` does the one-time work: normalize whitespace, segment the text, apply glue rules, measure the segments with canvas, and return an opaque handle. `layout()` is the cheap hot path after that: pure arithmetic over cached widths.
+`prepare()` does the one-time work: normalize whitespace, segment the text, apply glue rules, measure the segments with canvas, and return an opaque handle. `layout()` is the cheap hot path after that: pure arithmetic over cached widths. Do not rerun `prepare()` for the same text and configs; that'd defeat its precomputation. For example, on resize, only rerun `layout()`.
 
-If you want textarea-like text where ordinary spaces, `\t` tabs, and `\n` hard breaks stay visible, pass `{ whiteSpace: 'pre-wrap' }` to `prepare()` / `prepareWithSegments()`.
+If you want textarea-like text where ordinary spaces, `\t` tabs, and `\n` hard breaks stay visible, pass `{ whiteSpace: 'pre-wrap' }` to `prepare()`:
 
 ```ts
 const prepared = prepare(textareaValue, '16px Inter', { whiteSpace: 'pre-wrap' })