org: add an example for dealing with LTLf formulas

Related to issue #377.

* doc/org/tut12.org: New file.
* doc/org/tut.org, doc/Makefile.am, NEWS: Add the new file.
16 jobs for next in 323 minutes and 44 seconds (queued for 1 second)
Status Job ID Name Coverage
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passed #35821
alpine-gcc

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passed #35822
arch-clang

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arch-gcc-glibcxxdebug

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passed #35896
debian-gcc-snapshot

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debian-stable-gcc

00:43:22

passed #35819
debian-unstable-gcc-coverage

00:49:10

88.8%
passed #35826
debpkg-stable

03:16:11

failed #35934
debpkg-unstable

02:07:31

passed #35824
mingw-shared

00:08:57

passed #35825
mingw-static

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passed #35828
rpm-pkg

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failed #35820
debian-gcc-snapshot

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debpkg-unstable

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failed #35895
debpkg-unstable

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skipped #35829
dput
publish-rpm
skipped #35830
dput
publish-unstable
 
Name Stage Failure
failed
debpkg-unstable Build
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