docs: clarify copy_range destination behavior

[Gardner-Programs]

Summary

Closes #1550.

The dest parameter docstring for Worksheet.copy_range claimed the destination range size "has no effect" and that the source is always copied once regardless of dest. That is only true when dest is a single cell or smaller than the source. When dest is larger, the source is actually repeated to fill it, which is the behavior the issue reporter ran into and asked to have documented.

What changed

Doc-only. Rewrote the dest description to document the real behavior:

• The destination range does not need to match the source dimensions.
• If dest spans a multiple of the source's height or width, the source is repeated to fill the destination range.
• If dest is smaller than the source, the entire source is copied anyway, beyond the end of dest.

Also fixed grammar ("paste" -> "pasted", "is copies" -> "is copied") and added a CopyPasteRequest reference link next to the existing Paste Types link.

Verification

The behavior was confirmed two ways:

• Against Google's official CopyPasteRequest docs, which state: "If the range covers a span that's a multiple of the source's height or width, then the data will be repeated to fill in the destination range. If the range is smaller than the source range, the entire source data will still be copied."
• Live against the Sheets API: a one-row source pasted into a multi-row destination is repeated into each row, and a multi-row source repeats on exact multiples.

No code changes, so no tests or cassettes are affected.

[antoineeripret]

Great catch, thank you @Gardner-Programs !