diff docs/tutorial/test-training.t @ 4616:a78310b900e3

docs: change `troubles` references to `instability`

Per https://www.mercurial-scm.org/wiki/CEDVocabulary.  There are a couple
instances of 'troublesome' which probably need a word, as deriviatives of
'instability' didn't really fit.  At least some of these are in the unlinked
obs-terms.rst page.

--- a/docs/tutorial/test-training.t	Sat Apr 27 19:32:03 2019 -0400
+++ b/docs/tutorial/test-training.t	Sat Apr 27 19:42:42 2019 -0400
@@ -2550,7 +2550,7 @@
       	19 -> 20	 [penwidth=2.0];
       }
 
-Basic troubles + stabilization
+Basic instability + stabilization
 ------------------------------
 
   $ cp -R $TESTTMP/evolve_training_repo $TESTDIR/base-repos/edit-mid-stack/