Restore /reload-plugins step in telegram/discord READMEs

Partially reverts #758. The reload step is not redundant: the configure
skill runs before the restart step, so it is not loaded yet when the user
types /telegram:configure. CLI prints 'Run /reload-plugins to activate.'
after install (pluginInstallationHelpers.ts:529). Mintlify reports
confirm users hit 'Unknown skill: discord:configure' at step 3.

external_plugins/discord/README.md

@@ -47,8 +47,11 @@ These are Claude Code commands — run `claude` to start a session first.
 Install the plugin:
 ```
 /plugin install discord@claude-plugins-official
+/reload-plugins
 ```
 
+Check that `/discord:configure` tab-completes. If not, restart your session.
+
 **5. Give the server the token.**
 
 ```

external_plugins/telegram/README.md

@@ -27,8 +27,11 @@ These are Claude Code commands — run `claude` to start a session first.
 Install the plugin:
 ```
 /plugin install telegram@claude-plugins-official
+/reload-plugins
 ```
 
+Check that `/telegram:configure` tab-completes. If not, restart your session.
+
 **3. Give the server the token.**
 
 ```