Add 'Contributing' message (#1108)

Co-authored-by: RoBorg <roborg@gmail.com>

proto/otel/README.md

@@ -10,7 +10,7 @@
 
 OTLP exporting requires a [protobuf runtime library](https://github.com/protocolbuffers/protobuf/tree/main/php).
 
-There exist two protobuf runtime libraries that offer the same set of APIs, allowing developers to choose the one that 
+There exist two protobuf runtime libraries that offer the same set of APIs, allowing developers to choose the one that
 best suits their needs.
 
 This package requires `google/protobuf`, which is the native implementation. It is easy to install and a good way to get
@@ -24,3 +24,8 @@ pecl install protobuf
 ```
 
 The extension can be installed alongside the native library, and it will be used instead if available.
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/API/README.md

@@ -6,4 +6,9 @@
 
 # OpenTelemetry API
 
-Documentation: https://opentelemetry.io/docs/instrumentation/php
+Documentation: https://opentelemetry.io/docs/instrumentation/php
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/Context/README.md

@@ -55,4 +55,9 @@ function bindContext(Closure $closure): Closure {
 }
 ```
 
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).
+
 [1]: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/context/README.md#context

src/Contrib/Grpc/README.md

@@ -24,3 +24,8 @@ See https://github.com/open-telemetry/opentelemetry-php/blob/main/examples/trace
 $transport = (new \OpenTelemetry\Contrib\Grpc\GrpcTransportFactory())->create('http://collector:4317');
 $exporter = new \OpenTelemetry\Contrib\Otlp\SpanExporter($transport);
 ```
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/Contrib/Otlp/README.md

@@ -38,3 +38,8 @@ makes exporting _significantly_ more performant. This can be easily installed wi
 ```shell
 pecl install protobuf
 ```
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/Contrib/Zipkin/README.md

@@ -15,3 +15,8 @@ https://opentelemetry.io/docs/instrumentation/php/exporters/#zipkin
 ## Usage
 
 See https://github.com/open-telemetry/opentelemetry-php/blob/main/examples/traces/exporters/zipkin.php
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/Extension/Propagator/B3/README.md

@@ -24,4 +24,9 @@ B3Propagator::getB3MultiHeaderInstance()
 ```
 
 Both of the above have `extract` and `inject` methods available to extract and inject respectively into the
-header.  
+header.
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/SDK/README.md

@@ -42,3 +42,8 @@ $meter = \OpenTelemetry\API\Globals::meterProvider()->getMeter('example');
 If autoloading was not successful (or partially successful), no-op implementations of the above may be returned.
 
 See https://github.com/open-telemetry/opentelemetry-php/blob/main/examples/autoload_sdk.php for a more detailed example.
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).

src/SemConv/README.md

@@ -15,3 +15,8 @@ See https://opentelemetry.io/docs/concepts/semantic-conventions/.
 ```shell
 composer require open-telemetry/sem-conv
 ```
+
+## Contributing
+
+This repository is a read-only git subtree split.
+To contribute, please see the main [OpenTelemetry PHP monorepo](https://github.com/open-telemetry/opentelemetry-php).