[CF 5333] v1 - Document how to run only specific regress tests

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Patch(es): https://www.postgresql.org/message-id/CA+renyXB5jYG9r5-CaDc4g607EB398QwTk_efEXTzarrO8bPzw@mail.gmail.com
Author(s): Paul Jungwirth

Author: Commitfest Bot

doc/src/sgml/regress.sgml

@@ -125,6 +125,18 @@ make installcheck-parallel
   </para>
   </sect2>
 
+  <sect2 id="regress-subset">
+   <title>Running Specific Tests</title>
+
+   <para>
+    You can run a subset of the regression tests by saying
+    <literal>make check-tests TESTS="boolean char"</literal> or
+    <literal>make installcheck-tests TESTS="boolean char"</literal>.
+    Note that sometimes tests depend on each other, so you might get
+    extra failures.
+   </para>
+  </sect2>
+
   <sect2 id="regress-additional">
    <title>Additional Test Suites</title>