docs: Use conventional skills CLI package syntax

Author: smcllns

README.md

@@ -39,7 +39,7 @@ Installing or updating the Obsidian plugin does **not** automatically install an
 With the `skills.sh` CLI:
 
 ```bash
-bunx skills add https://github.com/smcllns/skills/tree/main/skills/obsidian-html-docs
+bunx skills add smcllns/skills --skill obsidian-html-docs
 ```
 
 ### Build and install from source