Update CHANGELOG.md

CHANGELOG.md

@@ -2,10 +2,28 @@
 
 ## Unreleased
 
+### 🛑 Breaking changes 🛑
+
+- (Splunk) Auto Instrumentation for Linux (manual installation/upgrade):
+  - The `/usr/lib/splunk-instrumentation/instrumentation.conf` config file is no longer
+    supported, and is replaced by `/etc/splunk/zeroconfig/java.conf`. If the `splunk-otel-auto-instrumentation` deb/rpm
+    package is manually upgraded, the options within `/usr/lib/splunk-instrumentation/instrumentation.conf` will need to
+    be manually migrated to their corresponding environment variables within `/etc/splunk/zeroconfig/java.conf`.
+  - Manual installation of the `splunk-otel-auto-instrumentation` deb/rpm package no longer automatically adds
+    `/usr/lib/splunk-instrumentation/libsplunk.so` to `/etc/ld.so.preload`.
+  - Manual upgrade of the `splunk-otel-auto-instrumentation` deb/rpm package will automatically remove
+    `/usr/lib/splunk-instrumentation/libsplunk.so` from `/etc/ld.so.preload`.
+  - The `splunk.linux-autoinstr.executions` metric is no longer generated by `libsplunk.so`.
+  - See [Splunk OpenTelemetry Zero Configuration Auto Instrumentation for Linux](https://github.com/signalfx/splunk-otel-collector/blob/main/instrumentation/README.md)
+    for manual installation/configuration details.
+
 ### 💡 Enhancements 💡
 
 - (Splunk) Update golang to 1.20.10 ([#3770](https://github.com/signalfx/splunk-otel-collector/pull/3770))
 - (Splunk) Add debian 12 support to installer ([#3766](https://github.com/signalfx/splunk-otel-collector/pull/3766))
+- (Splunk) Add new Auto Instrumentation options for the Linux installer script:
+  - `--with[out]-systemd-instrumentation`: Activate auto instrumentation for only `systemd` services without preloading the `libsplunk.so` shared object library (default: `--without-systemd-instrumentation`)
+  - `--otlp-endpoint host:port`: Set the OTLP gRPC endpoint for captured traces (default: `http://LISTEN_INTERFACE:4317` where `LISTEN_INTERFACE` is the value from the `--listen-interface` option if specified, or `127.0.0.1` otherwise)
 
 ## v0.86.0