require google/protobuf (native) (#1067)

We made protobuf implementation optional back in #949 however it seems to be tripping up
a number of developers. Since native + extension can be installed at the same time (with
extension taking priority), I think that users will be less surprised when starting out
if there is a working implementation by default.

README.md

@@ -8,20 +8,19 @@
 
 ## Protobuf Runtime library
 
+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 
 best suits their needs.
 
-The first and easiest option is to install the Protobuf PHP Runtime Library through composer. This can be the easiest 
-way to get started quickly. Either run `composer require google/protobuf`, or update your `composer.json` as follows:
-
-```json
-"require": {
-  "google/protobuf": "^v3.3.0"
-}
-```
+This package requires `google/protobuf`, which is the native implementation. It is easy to install and a good way to get
+started quickly.
 
 Alternatively, and the recommended option for production is to install the Protobuf C extension for PHP. The extension
-makes both exporters _significantly_ more performant. This can be easily installed with the following command:
-```sh
-$ sudo pecl install protobuf
+makes OTLP exporting _significantly_ more performant. The extension can be installed with the following command:
+
+```shell
+pecl install protobuf
 ```
+
+The extension can be installed alongside the native library, and it will be used instead if available.

composer.json

@@ -17,7 +17,8 @@
         }
     ],
     "require": {
-        "php": "^7.4 || ^8.0"
+        "php": "^7.4 || ^8.0",
+        "google/protobuf": "^3.3.0"
     },
     "autoload": {
         "psr-4": {
@@ -26,8 +27,7 @@
         }
     },
     "suggest": {
-        "ext-protobuf": "For better performance, when dealing with the protobuf format",
-        "google/protobuf": "To get started quickly, install the native protobuf library."
+        "ext-protobuf": "For better performance, when dealing with the protobuf format"
     },
     "extra": {
         "branch-alias": {