Add marketplace links to install table

Link to each assistant's marketplace directory. Anthropic is live;
OpenAI and Cursor are pending approval. GitHub Marketplace hosts
Copilot extensions. Direct plugin URLs replace these generic links
once listings are approved.

Author: mraible

README.md

@@ -21,8 +21,8 @@ AI coding assistant skills for building [CrowdStrike Falcon Foundry](https://www
 | Assistant | Command | Marketplace |
 |-----------|---------|-------------|
 | Claude Code | `/plugin install crowdstrike-falcon-foundry` | [Anthropic](https://claude.com/plugins/crowdstrike-falcon-foundry) |
-| Codex | `codex plugin add crowdstrike-falcon-foundry` | OpenAI (pending) |
-| Copilot CLI | `copilot plugin install CrowdStrike/foundry-skills` | |
+| Codex | `codex plugin add crowdstrike-falcon-foundry` | [OpenAI](https://chatgpt.com/plugins) (pending) |
+| Copilot CLI | `copilot plugin install CrowdStrike/foundry-skills` | [GitHub](https://github.com/marketplace?type=copilot-plugins) |
 | Cursor | `/add-plugin crowdstrike-falcon-foundry` | [Cursor](https://cursor.com/marketplace) (pending) |
 | Antigravity CLI | `agy plugin install https://github.com/CrowdStrike/foundry-skills` | |