docs: fix typo in opentracing doc (#150)

Author: axw

docs/opentracing.asciidoc

@@ -26,7 +26,7 @@ This bridge allows for different operation modes in combination with the Elastic
   If the `javaagent` is not specified, the bridge is in noop mode and does not actually record and report spans.
 - Mix and Match +
   If you want to leverage the auto instrumentation of Elastic APM,
-  but also want do create custom spans or use the OpenTracing API to add custom tags to the spanss created by Elastic APM,
+  but also want do create custom spans or use the OpenTracing API to add custom tags to the spans created by Elastic APM,
   you can just do that.
   The OpenTracing bridge and the standard Elastic APM API interact seamlessly.
 - Manual instrumentation +