autodie: Mention that "kill" is guarded under the ":ipc"-tag

Signed-off-by: Niels Thykier <niels@thykier.net>
Merge pull request #56 from nthykier/rt-97320

autodie: Mention that "kill" is guarded under the ":ipc"-tag
Fatal: Move up a variable to enable more reuse

Signed-off-by: Niels Thykier <niels@thykier.net>
Fatal: Remove a redundant if

Both paths basically compute the same end result.

Signed-off-by: Niels Thykier <niels@thykier.net>
Fatal: Rewrite/Reorder some comments

Signed-off-by: Niels Thykier <niels@thykier.net>
autodie: Mention that some builtins have prototype issues

Mention that e.g. chdir(BAREWORD) does not work (as usual) under
autodie due to differences in built-in behaviour vs. the prototype
Perl provides to us.

Signed-off-by: Niels Thykier <niels@thykier.net>