Docs: Update plan mode docs (#19682)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Jerop Kipruto <jerop@google.com>

docs/tools/planning.md

@@ -1,8 +1,8 @@
 # Gemini CLI planning tools
 
-Planning tools allow the Gemini model to switch into a safe, read-only "Plan
-Mode" for researching and planning complex changes, and to signal the
-finalization of a plan to the user.
+Planning tools let Gemini CLI switch into a safe, read-only "Plan Mode" for
+researching and planning complex changes, and to signal the finalization of a
+plan to the user.
 
 ## 1. `enter_plan_mode` (EnterPlanMode)
 
@@ -18,11 +18,12 @@ and planning.
 - **File:** `enter-plan-mode.ts`
 - **Parameters:**
   - `reason` (string, optional): A short reason explaining why the agent is
-    entering plan mode (e.g., "Starting a complex feature implementation").
+    entering plan mode (for example, "Starting a complex feature
+    implementation").
 - **Behavior:**
   - Switches the CLI's approval mode to `PLAN`.
   - Notifies the user that the agent has entered Plan Mode.
-- **Output (`llmContent`):** A message indicating the switch, e.g.,
+- **Output (`llmContent`):** A message indicating the switch, for example,
   `Switching to Plan mode.`
 - **Confirmation:** Yes. The user is prompted to confirm entering Plan Mode.
 
@@ -37,7 +38,7 @@ finalized plan to the user and requests approval to start the implementation.
 - **Parameters:**
   - `plan_path` (string, required): The path to the finalized Markdown plan
     file. This file MUST be located within the project's temporary plans
-    directory (e.g., `~/.gemini/tmp/<project>/plans/`).
+    directory (for example, `~/.gemini/tmp/<project>/plans/`).
 - **Behavior:**
   - Validates that the `plan_path` is within the allowed directory and that the
     file exists and has content.