Update install instructions to the one-command plugin install

Claude Code's /plugin install now registers the official marketplace
automatically and activates the plugin in the same session, so the
/reload-plugins step these READMEs document is no longer needed.

discord and telegram keep a conditional note because their MCP servers
can't always be activated mid-session.

external_plugins/discord/README.md

@@ -47,9 +47,10 @@ These are Claude Code commands — run `claude` to start a session first.
 Install the plugin:
 ```
 /plugin install discord@claude-plugins-official
-/reload-plugins
 ```
 
+If the install summary says to run `/reload-plugins`, run it — otherwise the plugin is active right away. (This plugin ships an MCP server, which can't always be activated mid-session.)
+
 **5. Give the server the token.**
 
 ```

external_plugins/telegram/README.md

@@ -27,9 +27,10 @@ These are Claude Code commands — run `claude` to start a session first.
 Install the plugin:
 ```
 /plugin install telegram@claude-plugins-official
-/reload-plugins
 ```
 
+If the install summary says to run `/reload-plugins`, run it — otherwise the plugin is active right away. (This plugin ships an MCP server, which can't always be activated mid-session.)
+
 **3. Give the server the token.**
 
 ```

plugins/claude-security/README.md

@@ -12,12 +12,13 @@ That makes it a natural fit for code you control — your own repositories, wher
 
 ## Installation
 
-Install from the official Anthropic marketplace, then reload plugins in the same session:
+Install from the official Anthropic marketplace:
 
     /plugin install claude-security@claude-plugins-official
-    /reload-plugins
 
-If Claude Code reports that the marketplace is not found, run `/plugin marketplace add anthropics/claude-plugins-official` first, then retry.
+Claude Code registers the marketplace automatically if it isn't already registered, and the plugin is active as soon as the install finishes — no reload step.
+
+If Claude Code reports that the marketplace is not found (older Claude Code versions), run `/plugin marketplace add anthropics/claude-plugins-official` first, then retry, and finish with `/reload-plugins`.
 
 
 ## Getting started