Add shortcuts hint and panel for discoverability (#18035)

docs/cli/commands.md

@@ -113,10 +113,14 @@ Slash commands provide meta-level control over the CLI itself.
   - **Description:** Lists all active extensions in the current Gemini CLI
     session. See [Gemini CLI Extensions](../extensions/index.md).
 
-- **`/help`** (or **`/?`**)
+- **`/help`**
   - **Description:** Display help information about Gemini CLI, including
     available commands and their usage.
 
+- **`/shortcuts`**
+  - **Description:** Toggle the shortcuts panel above the input.
+  - **Shortcut:** Press `?` when the prompt is empty.
+
 - **`/hooks`**
   - **Description:** Manage hooks, which allow you to intercept and customize
     Gemini CLI behavior at specific lifecycle events.

docs/cli/keyboard-shortcuts.md

@@ -128,6 +128,9 @@ available combinations.
 - `Option+B/F/M` (macOS only): Are interpreted as `Cmd+B/F/M` even if your
   terminal isn't configured to send Meta with Option.
 - `!` on an empty prompt: Enter or exit shell mode.
+- `?` on an empty prompt: Toggle the shortcuts panel above the input. Press
+  `Esc`, `Backspace`, or any printable key to close it. Press `?` again to close
+  the panel and insert a `?` into the prompt.
 - `\` (at end of a line) + `Enter`: Insert a newline without leaving single-line
   mode.
 - `Esc` pressed twice quickly: Clear the input prompt if it is not empty,