Update Getting Started section with Cowork and Claude Code instructions

- Add Cowork section with link to claude.com/plugins
- Update Claude Code commands to use current plugin marketplace syntax
  - claude plugin marketplace add for adding marketplace
  - claude plugin install for installing specific plugins

Author: lee-weisberger

README.md

@@ -30,12 +30,18 @@ Install these directly from Cowork, browse the full collection here on GitHub, o
 
 ## Getting Started
 
+### Cowork
+
+Install plugins from [claude.com/plugins](https://claude.com/plugins/).
+
+### Claude Code
+
 ```bash
-# Install from the plugin marketplace
-claude plugins add knowledge-work-plugins
+# Add the marketplace first
+claude plugin marketplace add anthropics/knowledge-work-plugins
 
-# Or install a specific plugin
-claude plugins add knowledge-work-plugins/sales
+# Then install a specific plugin
+claude plugin install sales@knowledge-work-plugins
 ```
 
 Once installed, plugins activate automatically. Skills fire when relevant, and slash commands are available in your session (e.g., `/sales:call-prep`, `/data:write-query`).