D1: std.md5: corrections for the given example

[Stewart Gordon]

downs wrote:
<snip>
> while (auto len = file.readBlock(buffer.ptr, buffer.sizeof))
<snip>

md5_example_2.d(7): expression expected, not 'auto'
md5_example_2.d(7): found 'len' when expecting ')'
md5_example_2.d(7): found '=' instead of statement

(this is line 7 after I removed comments and blank lines from your edit)

Stewart.