Rollup merge of #59498 - mbrubeck:write_all, r=Centril

Rollup merge of #59498 - mbrubeck:write_all, r=Centril

Use 'write_all' instead of 'write' in example code

Using `write` without looping and checking the result can cause silent data loss.  Example code should use `write_all` so that people don't copy this pattern.  (Of course this does not include example code for docs that are specifically about the `write` method.)