chore: Update Gemini.md rules to match existing style guide (googleapis#2982)

Removed the requirement for the title to end with 'Tool'.

Author: dishaprakash

DEVELOPER.md

@@ -530,7 +530,6 @@ When adding or updating a Source page, your markdown file must strictly adhere t
 When adding or updating a Tool page, your markdown file must strictly adhere to the following architectural rules:
 
   * **Location:** Native tools must be placed inside a nested `tools/` directory.
-  * **Frontmatter:** The `title` field must end with the word "Tool" (e.g., `title: "execute-sql Tool"`).
   * **No H1 Headings:** Do not use H1 (`#`) tags in the markdown body. The page title is automatically generated from the frontmatter.
   * **H2 Heading Hierarchy:** You must use H2 (`##`) headings in a strict, specific order.
       * **Required Headings:** `About`, `Example`

GEMINI.md

@@ -201,9 +201,8 @@ When generating or editing documentation for this repository, you must strictly
 ##### Tool Page Constraints (`integrations/**/tools/*.md`)
 
 1.  **Location:** All native tools must reside inside a nested `tools/` subdirectory. The `tools/` directory must contain an `_index.md` file consisting **strictly of frontmatter**.
-2.  **Title Convention:** The YAML frontmatter `title` must always end with "Tool" (e.g., `title: "Execute SQL Tool"`).
-3.  **No H1 Tags:** Never generate H1 (`#`) headings in the markdown body.
-4.  **Strict H2 Ordering:** You must use the following H2 (`##`) headings in this exact sequence.
+2.  **No H1 Tags:** Never generate H1 (`#`) headings in the markdown body.
+3.  **Strict H2 Ordering:** You must use the following H2 (`##`) headings in this exact sequence.
     *   `## About` (Required)
     *   `## Compatible Sources` (Optional)
     *   `## Requirements` (Optional)
@@ -214,7 +213,7 @@ When generating or editing documentation for this repository, you must strictly
     *   `## Advanced Usage` (Optional)
     *   `## Troubleshooting` (Optional)
     *   `## Additional Resources` (Optional)
-5.  **Shortcode Placement:** If you generate the `## Compatible Sources` section, you must include the `{{< compatible-sources >}}` shortcode beneath it.
+4.  **Shortcode Placement:** If you generate the `## Compatible Sources` section, you must include the `{{< compatible-sources >}}` shortcode beneath it.
 
 ##### Samples Architecture Constraints
 Sample code is aggregated visually in the UI via the Samples section, but the physical markdown files are distributed logically based on their scope.