help: clarify the choice of pager
This follows the change made in
d83e51654c8a to use environment variables
between system and user configuration.
--- a/mercurial/help/pager.txt Fri Jun 02 20:50:46 2017 -0300
+++ b/mercurial/help/pager.txt Fri Jun 02 10:44:40 2017 +0200
@@ -6,9 +6,10 @@
[pager]
pager = less -FRX
-If no pager is set, Mercurial uses the environment variable
-$PAGER. If neither pager.pager, nor $PAGER is set, a default pager
-will be used, typically `less` on Unix and `more` on Windows.
+If no pager is set in the user or repository configuration, Mercurial uses the
+environment variable $PAGER. If $PAGER is not set, pager.pager from the default
+or system configuration is used. If none of these are set, a default pager will
+be used, typically `less` on Unix and `more` on Windows.
.. container:: windows