Fix incorrect 'memory leak' example for Vec::set_len.

[frewsxcv]

Example was written in #34911

Issue was brought up in this comment:

a005b2c#commitcomment-18346958

[rust-highfive]

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[nagisa]

I feel like a using a Box instead of Vec for elements would get the point across better.

[frewsxcv]

I feel like a using a Box instead of Vec for elements would get the point across better.

In what ways do you think a Box would be more appropriate here?

[frewsxcv]

r? @GuillaumeGomez

[GuillaumeGomez]

I'd prefer to let @nagisa or someone else handles this PR.

[nagisa]

This PR is correct for all its worth.

[GuillaumeGomez]

@nagisa: Then r+ it :p

[nagisa]

r=me, I guess.

[GuillaumeGomez]

@bors: r=nagisa

[bors]

📌 Commit 1e0043e has been approved by nagisa