Add documentation for .roomodes feature

Fixes #8

Add detailed documentation for the `.roomodes` feature in a new `README-roomodes.md` file.

* **Overview**: Describe the `.roomodes` feature and its purpose.
* **Creating and Managing Custom Modes**: Provide step-by-step instructions on how to create and manage custom modes in the `.roomodes` file.
* **Precedence of .roomodes over Global Settings**: Explain how project-specific modes in `.roomodes` take precedence over global settings.
* **Examples of Valid .roomodes Configurations**: Include examples of valid `.roomodes` configurations, such as adding a new mode, overriding an existing mode, and a mode with file restrictions.

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For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/richardwhiteii/Roo-Code/issues/8?shareId=XXXX-XXXX-XXXX-XXXX).

Author: richardwhiteii

README-roomodes.md

@@ -0,0 +1,105 @@
+# .roomodes Feature Documentation
+
+## Overview
+
+The `.roomodes` feature in Roo-Code allows you to define project-specific custom modes. These custom modes can override global modes or add new modes specific to a project. The `.roomodes` file is placed in the root directory of your project and contains the configuration for these custom modes.
+
+## Creating and Managing Custom Modes
+
+To create and manage custom modes in `.roomodes`, follow these steps:
+
+1. **Create the `.roomodes` file**: In the root directory of your project, create a file named `.roomodes`.
+
+2. **Define custom modes**: Add the custom modes configuration in JSON format. Each mode should have a unique `slug`, a `name`, a `roleDefinition`, and an array of `groups`. Optionally, you can add `customInstructions`.
+
+Example `.roomodes` file:
+```json
+{
+  "customModes": [
+    {
+      "slug": "designer",
+      "name": "Designer",
+      "roleDefinition": "You are Roo, a UI/UX expert specializing in design systems and frontend development. Your expertise includes:\n- Creating and maintaining design systems\n- Implementing responsive and accessible web interfaces\n- Working with CSS, HTML, and modern frontend frameworks\n- Ensuring consistent user experiences across platforms",
+      "groups": [
+        "read",
+        "edit",
+        "browser",
+        "command",
+        "mcp"
+      ],
+      "customInstructions": "Additional instructions for the Designer mode"
+    }
+  ]
+}
+```
+
+3. **Save the file**: Save the `.roomodes` file in the root directory of your project.
+
+## Precedence of .roomodes over Global Settings
+
+When both global custom modes and project-specific custom modes are defined, the project-specific modes in `.roomodes` take precedence. This means that if a mode with the same `slug` exists in both the global settings and `.roomodes`, the configuration in `.roomodes` will be used.
+
+## Examples of Valid .roomodes Configurations
+
+Here are some examples of valid `.roomodes` configurations:
+
+### Example 1: Adding a New Mode
+```json
+{
+  "customModes": [
+    {
+      "slug": "data-scientist",
+      "name": "Data Scientist",
+      "roleDefinition": "You are Roo, a data scientist with expertise in data analysis, machine learning, and statistical modeling.",
+      "groups": [
+        "read",
+        "edit",
+        "command"
+      ],
+      "customInstructions": "Focus on data analysis and machine learning tasks."
+    }
+  ]
+}
+```
+
+### Example 2: Overriding an Existing Mode
+```json
+{
+  "customModes": [
+    {
+      "slug": "code",
+      "name": "Code",
+      "roleDefinition": "You are Roo, a highly skilled software engineer with extensive knowledge in many programming languages, frameworks, design patterns, and best practices.",
+      "groups": [
+        "read",
+        "edit",
+        "browser",
+        "command",
+        "mcp"
+      ],
+      "customInstructions": "Additional instructions for the Code mode"
+    }
+  ]
+}
+```
+
+### Example 3: Mode with File Restrictions
+```json
+{
+  "customModes": [
+    {
+      "slug": "markdown-editor",
+      "name": "Markdown Editor",
+      "roleDefinition": "You are Roo, a markdown editor with expertise in editing and formatting markdown files.",
+      "groups": [
+        "read",
+        ["edit", { "fileRegex": "\\.md$", "description": "Markdown files only" }],
+        "browser"
+      ],
+      "customInstructions": "Focus on editing and formatting markdown files."
+    }
+  ]
+}
+```
+
+By following these instructions, you can create and manage custom modes in your project using the `.roomodes` feature in Roo-Code.