[PATCH] git-status: Document type changed status

Note: I composed this email manually because I could not get `git send-email` to work. I apologize for any additional trouble this causes and would appreciate any help to properly set it up.
`git send-email` with `--smtp-debug=1`:
```
Send this email? ([y]es|[n]o|[q]uit|[a]ll): y
Net::SMTP>>> Net::SMTP(2.31)
Net::SMTP>>>   Net::Cmd(2.29)
Net::SMTP>>>     Exporter(5.68)
Net::SMTP>>>   IO::Socket::INET(1.33)
Net::SMTP>>>     IO::Socket(1.36)
Net::SMTP>>>       IO::Handle(1.34)
Net::SMTP: Unexpected EOF on command channel at /Applications/Xcode.app/Contents/Developer/usr/libexec/git-core/git-send-email line 1499.
Unable to initialize SMTP properly. Check config and use --smtp-debug. VALUES: server=secure.emailsrvr.com encryption=tls hello=terra.telenet.be port=465 at /Applications/Xcode.app/Contents/Developer/usr/libexec/git-core/git-send-email line 1527.
```

Below the `git format-patch` output:

`git status -s` output a T for me after replacing a file with a symlink. I'd never seen this status so I checked `git help status` but "T" wasn't documented. `man git-diff-files` does have it listed among the possible statuses.

I added both the terse description in the list of statuses and two lines to the table explaining the difference between occuring in the X or Y position. Improvements to both wording and formatting are welcome.

Signed-off-by: toonn <toonn@toonn.io>
---
 Documentation/git-status.txt | 4 ++++
 1 file changed, 4 insertions(+)