replace create_agent with create_react_agent and prebuilts with prebuilt

[mcavdar]

Overview

fixed typos. Corrected langgraph.prebuilts → langgraph.prebuilt and create_agent → create_react_agent

Type of change

Type: Fix typo

Related issues/PRs

• GitHub issue:
• Feature PR:

• Linear issue:
• Slack thread:

Checklist

• I have read the contributing guidelines
• I have tested my changes locally using docs dev
• All code examples have been tested and work correctly
• I have used root relative paths for internal links
• I have updated navigation in src/docs.json if needed
• I have gotten approval from the relevant reviewers
• (Internal team members only / optional) I have created a preview deployment using the Create Preview Branch workflow

Additional notes