Update variables.md

Added "and" as it was missing.
- when you are looping in a range need to know the chart's release
+ when you are looping in a range and need to know the chart's release

docs/chart_template_guide/variables.md

@@ -100,7 +100,7 @@ Variables are normally not "global". They are scoped to the block in which they
 
 However, there is one variable that is always global - `$` - this
 variable will always point to the root context.  This can be very
-useful when you are looping in a range need to know the chart's release
+useful when you are looping in a range and need to know the chart's release
 name.
 
 An example illustrating this: