[std] Fix colons in front of bulleted lists

[jensmaurer]

Fixes #6999

[tkoeppe]

Thank you, but we shan't need this as the status quo is acceptable.

[jensmaurer]

@tkoeppe

We do need this, because the status quo is inconsistent: Our rule is "bullets are whitespace", and this patch thus removes the colons where none are needed. (ISO wants us to add more colons, which we don't want to do.)

[tkoeppe]

Aha, OK, let me take a closer look, thanks!