feat(knowledge): add cli and update docs

cli/cli.py

@@ -6,6 +6,7 @@ from cli.commands.skill import skill
 from cli.commands.process import start, stop, restart, update, status, logs
 from cli.commands.context import context
 from cli.commands.install import install_browser
+from cli.commands.knowledge import knowledge
 
 
 HELP_TEXT = """Usage: cow COMMAND [ARGS]...
@@ -22,6 +23,7 @@ Commands:
   status   Show CowAgent running status.
   logs     View CowAgent logs.
   skill    Manage CowAgent skills.
+  knowledge  Manage knowledge base.
   install-browser  Install browser tool (Playwright + Chromium).
 
 Tip: You can also send /help, /skill list, etc. in agent chat."""
@@ -69,6 +71,7 @@ main.add_command(update)
 main.add_command(status)
 main.add_command(logs)
 main.add_command(context)
+main.add_command(knowledge)
 main.add_command(install_browser)