Update README

Author: jhc13

README.md

@@ -1 +1,62 @@
 # Image Tagging GUI
+
+Cross-platform desktop application for quickly tagging images, aimed towards
+creators of image datasets for generative AI.
+Written in Python using PySide6.
+
+## Features
+
+- Keyboard-friendly interface for fast tagging
+- Tag autocomplete based on your most used tags
+- Integrated token counter
+- Searchable list of all used tags
+- Filter images by tag
+- Rename or delete all instances of a tag
+- Automatic dark mode based on system settings
+
+## Installation
+
+The easiest way to use the application is to download the latest release from
+the [releases page](https://www.github.com/jhc13/image-tagging-gui/releases).
+The executable file can be run directly without any additional dependencies.
+
+Alternatively, you can install manually by cloning this repository and
+installing the dependencies in `requirements.txt`.
+Run `image-tagging-gui/run_gui.py` to start the program.
+Python 3.11 is recommended, but Python 3.10 should also work.
+
+## Usage
+
+Load the directory containing your images by clicking the `Load Directory`
+button in the center of the window (or `File` -> `Load Directory`).
+Tags are loaded from `.txt` files in the directory with the same names as the
+images.
+Any changes you make to the tags are also automatically saved to these `.txt`
+files.
+
+You can change the settings in `File` -> `Settings`.
+Panes can be resized, undocked, and moved around.
+
+## Controls
+
+### Images pane
+
+- Previous / next image: `Up` / `Down` arrow keys
+- First / last image: `Home` / `End`
+
+### Image Tags pane
+
+- Add a tag: Type the tag into the `Add Tag` box and press `Enter`
+- Add the first tag suggested by autocomplete: Press `Ctrl`+`Enter`
+- Delete a tag: Select the tag and press `Delete`
+- Rename a tag: Double-click the tag, or select the tag and press `F2`
+- Reorder tags: Drag and drop the tags
+- Select multiple tags: Hold `Ctrl` or `Shift` while selecting the tags
+
+### All Tags pane
+
+- Show all images containing a tag: Select the tag
+- Go back to showing all images: Click the `Clear Image Filter` button 
+- Delete all instances of a tag: Select the tag and press `Delete`
+- Rename all instances of a tag: Double-click the tag, or select the tag and
+  press `F2`