Add troubleshooting information

[koutcher]

No description provided.

[jonas]

LGTM, I don't know if it would make sense to link to this page from the README's bug reporting section.

[jonas]

TIL 🤩

[koutcher]

LGTM, I don't know if it would make sense to link to this page from the README's bug reporting section.

Good idea. Is this appropriate ?

 Bugs and Feature Requests
 -------------------------
+Please check out the
+https://github.com/jonas/tig/blob/master/TROUBLESHOOTING.adoc[troubleshooting guide]
+if you are experiencing issues with Tig.
+
 Bugs and feature requests can be reported using the

[jonas]

Yes, or we could also add it to book.md to make it part of the documentation site and link to it "relatively" using

link:TROUBLESHOOTING.{docext}[troubleshooting guide]

I can do that if you prefer in a future PR.

[koutcher]

I have pushed my current state to the PR, I'll be happy if you want to take the lead on it. Edit at your convenience.

[krobelus]

I get

$ locale -a
C
en_US.utf8
POSIX
$ echo $LANG
en_US.UTF-8

and I think it works fine, so I guess

Suggested change

	use `locale -a | grep "$LANG"`.
	use `locale -a | grep -i "$LANG"`.

[koutcher]

Thanks for reporting, looks like utf8 is a Linux oddity. -i won't help because of the missing hyphen. So I'd rather reword to:

-To check that your locale is present in the list of available locales,
-use `locale -a | grep "$LANG"`.
+Use `locale -a` to check if your `LANG` variable is present in the
+list of available locales (on Linux, you may find that `UTF-8` has
+been substituted for `utf8` but they are equivalent).

[krobelus]

Sounds good, thanks!
systemd's localectl list-locales uses en_US.UTF-8, but of course that's not available elsewhere.

[krobelus]

Suggested change

	Note that the ability to set the `LANG` variable to values such as
	`en_DE` with KDE does not infer their validity.
	Note that the ability to set the `LANG` variable to values such as
	`en_DE` with KDE does not imply their validity.

[krobelus]

Suggested change

	Some OS (e.g. OS X 10.11) are shipping with an incomplete terminfo
	description for screen resulting, for example, in diff-highlight option
	Some OS (e.g. OS X 10.11) are shipping with an incomplete terminfo
	description for screen resulting, for example, in the diff-highlight option