view: add [thread overview] anchor next to Date:
The existing Subject: anchor to #r may not be 100% obvious,
and we can't stick the phrase "[thread overview]" into the
same line as the Subject without introducing ambiguity.
Fortunately, we have the Date: header directly under it.
Adding "[thread overview]" after the Date: is unambiguous
and won't make the line too long for valid emails.
This hopefully improves navigation ever-so-slightly thanks
to comments by Son Luong Ngoc.
Reported-by: Son Luong Ngoc <sluongng@gmail.com>
Link: https://public-inbox.org/git/YHhfsqfTJ9NzRwS1@C02YX140LVDN.corpad.adbkng.com/