Document the 0.8.1 workflow features in README Description

[djdcks12]

Description

0.8.1 added several user-facing workflow features, but the README still reads more like the pre-0.8 guide in some sections. The changelog explains the features in detail, but new users usually read the README first.

The README should briefly explain the new workflow surfaces:

• Validate: compile the current snippet without executing it.
• Insert into Code: insert snippets from Output tree, Object Browser, and Watch rows.
• Named Pins: bind live values as session names such as player, manager, or popup.
• Pins window: inspect and clear current session pins from Tools / Roslyn REPL / Pins….

Why

These features reduce friction in the main REPL loop, but they are easy to miss if they only appear in the changelog or hidden context menus.

Suggested Fix

Update the README user guide with short, workflow-oriented sections for:

• Validate before running risky snippets.
• Insert values back into the Code editor.
• Pin frequently used live objects by name.
• Manage pins from the Pins window.

Keep this user-facing and concise. The README should explain what the feature helps the user do, not all implementation details.

Acceptance Criteria

• README mentions Validate and clearly says it does not run code.
• README mentions Insert into Code and the surfaces where it appears.
• README mentions Named Pins and gives at least one example such as return player.transform.position;.
• README mentions Tools / Roslyn REPL / Pins….
• README_KR is updated with the same meaning.