meson: Update json-control help description

Attempt to better specify what the json-control meson option does, which
is to allow one to use YAML based fan control even when everything else
uses JSON because the json-config option was enabled.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I08531b16a707792ad79ef2dabd8320327ce7f1e4
diff --git a/meson_options.txt b/meson_options.txt
index 50a8b4f..718ca7f 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -22,7 +22,10 @@
 
 option(
     'json-control', type: 'feature', value: 'enabled',
-    description: 'Disable JSON based fan control even if json-config is enabled.'
+    description: '''This can only be used to disable JSON based fan control
+                    (using json-control=disabled) when json-config is enabled.
+                    If json-control=enabled and json-config=disabled it will
+                    not do anything.'''
 )
 
 option(