clarify wording of running the complete test suite before commit

Co-authored-by: Harry Percival <[email protected]>

Author: Xronophobe

chapter_12_organising_test_files.asciidoc

@@ -381,9 +381,10 @@ AssertionError: write me!
 Brilliant--no need to sit around waiting for all the FTs
 when we're only interested in a single one.
 Although we need to remember to run all of them now and again, to check for regressions.
-It's a good habit to run all the tests before making a `git commit`.
-Later in the book we'll see how to give that task over to an automated Continuous Integration loop.
-For now, let's commit!
+Later in the book we'll set up a Continuous Integration (CI) server to run all the tests automatically,
+for example every time we push to master.
+For now, a good prompt for running all the tests is "just before you do a commit",
+so let's get into that habit now:
 
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