Minor fix to counter metric types description - fix original commit (#1043)

Signed-off-by: James Turnbull <james@lovedthanlost.net>

content/docs/concepts/metric_types.md

@@ -20,8 +20,7 @@ use a counter to represent the number of requests served, tasks completed, or
 errors.
 
 Do not use a counter to expose a value that can decrease. For example, do not
-use a counter for the number of currently running processes, but use a gauge
-instead.
+use a counter for the number of currently running processes; instead use a gauge.
 
 Client library usage documentation for counters: