chore: update url to OTEP 0243 (#1011)

The OTEPs repo was migrated to a new location and the old repo was
archived. That's why a url update is needed.

Signed-off-by: Jovan Kostovski <[email protected]>

Author: chombium

README.md

@@ -67,7 +67,7 @@ Weaver provides a _set of tools_ for working with **schematized telemetry**.
 
 Further reading:
 - [Weaver Architecture](docs/architecture.md): A document detailing the architecture of the project.
-- [Application Telemetry Schema OTEP](https://github.com/open-telemetry/oteps/blob/main/text/0243-app-telemetry-schema-vision-roadmap.md): A vision and roadmap for the concept of Application Telemetry Schema.
+- [Application Telemetry Schema OTEP](https://github.com/open-telemetry/opentelemetry-specification/blob/main/oteps/0243-app-telemetry-schema-vision-roadmap.md): A vision and roadmap for the concept of Application Telemetry Schema.
 
 ## Examples and How-Tos