[master] 6e1c2b6ba document the happy counter

[Nils Goroll]

commit 6e1c2b6ba3b5d5a32c0a9ef125eeaf0a6440a794
Author: Guillaume Quintard <guillaume at varnish-software.com>
Date:   Tue Feb 23 17:46:41 2021 -0800

    document the happy counter

diff --git a/bin/varnishd/VSC_vbe.vsc b/bin/varnishd/VSC_vbe.vsc
index c26207af9..52fa1806b 100644
--- a/bin/varnishd/VSC_vbe.vsc
+++ b/bin/varnishd/VSC_vbe.vsc
@@ -12,6 +12,10 @@
 	:level:	info
 	:oneliner:	Happy health probes
 
+	Represents the last probe results as a bitmap. Happy probes are bits set
+	to 1, and the unhappy ones are set to 0. The highest bits represent the
+	oldest probes.
+
 .. varnish_vsc:: bereq_hdrbytes
 	:type:	counter
 	:level:	info