docs: Corrected the number of built-in subagents in documentation (#6133)

packages/web/src/content/docs/agents.mdx

@@ -42,7 +42,7 @@ OpenCode comes with two built-in subagents, **General** and **Explore**. We'll l
 
 ## Built-in
 
-OpenCode comes with two built-in primary agents and one built-in subagent.
+OpenCode comes with two built-in primary agents and two built-in subagents.
 
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