Add usage guide to README covering main features

Co-Authored-By: Mr_Rosh <teddrosh95@gmail.com>

README.md

@@ -5,3 +5,76 @@ Original: http://www.curse.com/addons/wow/colorpickerplus
 Adds improved features to the existing Blizzard color picker widget. Features
 like copying and pasting colors, RGBA channel values, hex value and color
 swatches for the old color and color in the copy buffer.
+
+## Usage Guide
+
+ColorPickerPlus enhances the standard Blizzard color picker by adding precise
+color input, copy/paste support, and visual color swatches. Once installed, these
+features appear automatically whenever the in-game color picker opens.
+
+### Text Entry for RGB and Hex Values
+
+Instead of relying solely on the color wheel, you can type exact color values
+directly into the input fields at the bottom of the color picker:
+
+- **R, G, B fields** — Enter individual red, green, and blue channel values
+  from 0 to 255 for precise numeric control over each color component.
+- **Hex field (#)** — Enter a 6-character hex color code (e.g. `FF5A00`) to set
+  all three channels at once. This is useful when matching colors from external
+  design tools or web references.
+- **Alpha field (A)** — When the color picker includes an opacity option, an
+  alpha field appears. Enter a value from 0 to 100 to set the opacity
+  percentage.
+
+All fields stay in sync: changing the RGB values updates the hex field
+automatically, and entering a hex code updates the individual R, G, and B
+values. You can press **Tab** to cycle between the fields in order
+(R → G → B → Hex → Alpha → R).
+
+### Copy and Paste Colors
+
+Two buttons are added to the color picker dialog:
+
+- **Copy** — Saves the currently selected color (and alpha, if applicable) to an
+  internal buffer. A swatch showing the copied color appears below the Paste
+  button.
+- **Paste** — Applies the previously copied color to the picker, instantly
+  setting the RGB values and alpha. This button is disabled until a color has
+  been copied.
+
+This lets you reuse a color across different UI elements without having to
+remember or re-enter the values each time.
+
+> **Tip:** Hold **Shift** and click **Copy** to print the raw decimal color
+> values (0.000–1.000) to the chat window — handy for addon development and
+> macro scripting.
+
+### Color Swatches
+
+Two color swatches are displayed alongside the current color swatch:
+
+- **Starting color swatch** — Shows the original color that was set before you
+  opened the picker, so you can always compare your changes against the
+  previous color.
+- **Copied color swatch** — Shows the color currently stored in the copy buffer
+  after pressing Copy, giving you a visual reference of the saved color.
+
+### Movable Color Picker
+
+The color picker frame can be dragged around the screen by clicking and dragging
+its title bar area. It is clamped to the screen edges so it cannot be moved
+out of view.
+
+### How These Features Enhance the Standard Color Picker
+
+The default Blizzard color picker only provides a color wheel and brightness
+slider, making it difficult to select an exact color or reuse one across
+different settings. ColorPickerPlus solves these limitations by adding:
+
+| Feature              | Standard Picker | With ColorPickerPlus            |
+|----------------------|-----------------|---------------------------------|
+| Color input method   | Wheel only      | Wheel, RGB fields, and hex code |
+| Color reuse          | Not supported   | Copy and paste between pickers  |
+| Previous color ref   | Not shown       | Starting color swatch           |
+| Opacity text entry   | Slider only     | Slider and numeric field        |
+| Repositioning        | Fixed position  | Draggable frame                 |