Fix typo in README.md (ARM-software#16)

AttilioProvenzano-ARM · wasimabbas-arm · commit 34cad32a7d09 · 2019-05-17T15:22:33.000+01:00
diff --git a/README.md b/README.md
@@ -83,7 +83,7 @@ if (measurements.cpu)
     if (counter != measurements.cpu->end())
     {
         // Get the data stored in the counter, casted to the type you need
-        auto value = cpu_res->counter.get<float>();
+        auto value = counter->second.get<float>();
     }
 }
 ```

Original file line number	Diff line number	Diff line change
`@@ -83,7 +83,7 @@ if (measurements.cpu)`
`83`	`83`	`if (counter != measurements.cpu->end())`
`84`	`84`	`{`
`85`	`85`	`// Get the data stored in the counter, casted to the type you need`
`86`		`- auto value = cpu_res->counter.get<float>();`
	`86`	`+ auto value = counter->second.get<float>();`
`87`	`87`	`}`
`88`	`88`	`}`
`89`	`89`	```