As the command hint by SSH key verification shows echo -n "token" | ... which including trailing new line symbol by PowerShell and makes the wrong signature for the verification process.

That means only Linux and macOS can work properly with the origin command hint.
This PR shows what the command hints that Windows user could be easily calculated the correct signature value as Linux does.

ref: PowerShell/PowerShell#5974 (comment)

And I also make the command hints collapse to minimize the section.

Output

I think we could remove the "Linux & macOS" hint because it works for all POSIX standard shells.

And I think we can simplify the template by removing the printf, will make some changes here, just a moment.

And one more question: are these "quotes" necessary?

Should we detect user's OS from the web browser and display the right command?

Should we detect user's OS from the web browser and display the right command?

I prefer to keep it simple, do not introduce too much JS code

And one more question: are these "quotes" necessary?

As the output I just tried on my PowerShell, the quotes are necessary.

As the output I just tried on my PowerShell, the quotes are necessary.

But the real output is a string which only contains letters&numbers, there is no < or >. Then is the `" still necessary?

As the output I just tried on my PowerShell, the quotes are necessary.

But the real output is a string which only contains letters&numbers, there is no < or >. Then is the `" still necessary?

So here is my output

## Correct
PS > cmd /c "<NUL set /p=`"b6320474e4ee14cbedf20856d5371904f23bc8beea20c5358d1cee7379cf3d66`"| ssh-keygen -Y sign -n gitea -f id_ed25519"
Signing data on standard input
-----BEGIN SSH SIGNATURE-----
U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgmjx3mDaLWkLlHptkELlfNhgA8J
FcHFn3m+ODd68ufggAAAAFZ2l0ZWEAAAAAAAAABnNoYTUxMgAAAFMAAAALc3NoLWVkMjU1
MTkAAABA0AR+1fJyD9G+at8fSEdQJsx+f7Od0FmvFcr3P53V9bTDKwIJAMs0SR3Q86CpHT
ELsuRdTlR3S62Bb9J9JDbyAg==
-----END SSH SIGNATURE-----

## Wrong
PS > cmd /c "<NUL set /p=b6320474e4ee14cbedf20856d5371904f23bc8beea20c5358d1cee7379cf3d66| ssh-keygen -Y sign -n gitea -f id_ed25519"
Signing data on standard input
-----BEGIN SSH SIGNATURE-----
U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgmjx3mDaLWkLlHptkELlfNhgA8J
FcHFn3m+ODd68ufggAAAAFZ2l0ZWEAAAAAAAAABnNoYTUxMgAAAFMAAAALc3NoLWVkMjU1
MTkAAABAVrx4k+c7wELor/jRErKKABPaOjiTJoCJ0iQgZeyRhxaLRF0LxdwB6EeEe2G2lh
BPBwnr6DiLeqt89Tg7nPgoDg==
-----END SSH SIGNATURE-----

And I also tried with /p=`xxxx`, the output isn't the correct one

Interesting .... Windows command line has too many quirks ....

Now I think now the generated commands should be the same as the initial ones by your first commit.

kind of magic, both of PowerShell & CMD