Add readme for dataset annotator (#847)

dataset/README.md

@@ -0,0 +1,23 @@
+# Dataset annotation tool
+
+SHARK annotator for adding or modifying prompts of dataset images
+
+## Set up
+
+Activate SHARK Python virtual environment and install additional packages
+```shell
+source ../shark.venv/bin/activate
+pip install -r requirements.txt
+```
+
+## Run annotator
+
+```shell
+python annotation_tool.py
+```
+* Select dataset from `Dataset` dropdown list
+* Select image from `Image` dropdown list
+* Image and the existing prompt will be loaded
+* Add or modify prompt in `Prompt` textbox which will be autosaved
+* Click `Next` to load the next image, you could also select other images from `Image`
+* Click `Finish` when finishing annotation or before switching dataset