Add SectionPreamble to go/README SystemMessage keys list

MackinnonBuck · Copilot · MackinnonBuck · commit 077a390421fb · 2026-06-18T08:36:41.000-07:00
The SystemMessage parameter-reference table's inline section-constant
list still started at SectionIdentity. Add SectionPreamble so it matches
the dedicated 'Available section constants' list and the other SDKs.

Co-authored-by: Copilot &lt;223556219+Copilot@users.noreply.github.com&gt;
diff --git a/go/README.md b/go/README.md
@@ -165,7 +165,7 @@ Event types: `SessionLifecycleCreated`, `SessionLifecycleDeleted`, `SessionLifec
 - `SystemMessage` (\*SystemMessageConfig): System message configuration. Supports three modes:
   - **append** (default): Appends `Content` after the SDK-managed prompt
   - **replace**: Replaces the entire prompt with `Content`
-  - **customize**: Selectively override individual sections via `Sections` map (keys: `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`, `SectionRuntimeInstructions`, `SectionLastInstructions`; values: `SectionOverride` with `Action` and optional `Content`)
+  - **customize**: Selectively override individual sections via `Sections` map (keys: `SectionPreamble`, `SectionIdentity`, `SectionTone`, `SectionToolEfficiency`, `SectionEnvironmentContext`, `SectionCodeChangeRules`, `SectionGuidelines`, `SectionSafety`, `SectionToolInstructions`, `SectionCustomInstructions`, `SectionRuntimeInstructions`, `SectionLastInstructions`; values: `SectionOverride` with `Action` and optional `Content`)
 - `Provider` (\*ProviderConfig): Custom API provider configuration (BYOK). See [Custom Providers](#custom-providers) section.
 - `Streaming` (*bool): Enable streaming delta events (nil = runtime default)
 - `InfiniteSessions` (\*InfiniteSessionConfig): Automatic context compaction configuration
