docs: Fix otcollector README (open-telemetry#500)

Fixes % python -m readme_renderer ext/opentelemetry-ext-otcollector/README.rst
<string>:22: (ERROR/3) Unknown target name: "opentelemetry".

Author: c24t

ext/opentelemetry-ext-otcollector/README.rst

@@ -95,4 +95,4 @@ References
 ----------
 
 * `OpenTelemetry Collector <https://github.com/open-telemetry/opentelemetry-collector/>`_
-* `OpenTelemetry Project <https://opentelemetry.io/>`_
+* `OpenTelemetry <https://opentelemetry.io/>`_