Update tagging explanation in readme

Make it more clear that the main branch contains the most up to date
version, give an example of how to load a specific tag, and list the
most recent 4 tags.

README.md

@@ -13,11 +13,40 @@ tags:
 
 # LMSYS Chatbot Arena ELO Scores
 
-This dataset is a datasets-friendly version of Chatbot Arena ELO scores,
+This dataset is a `datasets`-friendly version of Chatbot Arena ELO scores,
 updated daily from the leaderboard API at
 https://huggingface.co/spaces/lmarena-ai/chatbot-arena-leaderboard.
 
-Most recent tag: 20241024
+**Updated: 20241024**
+
+## Loading Data
+
+```python
+from datasets import load_dataset
+
+dataset = load_dataset("mathewhe/chatbot-arena-elo", split="train")
+```
+
+The main branch of this dataset will always be updated to the latest ELO and
+leaderboard version. If you need a fixed dataset that does not change, please
+specify a date tag when loading the dataset:
+
+```python
+from datsasets import load_dataset
+
+# Load the leaderboard from October 24, 2024
+dataset = load_dataset("mathewhe/chatbot-arena-elo", split="train", revision="20241024")
+```
+
+Tags are only created when the leaderboard is updated. See below for a list of
+recent tags.
+
+```
+20241024
+20241023
+20241020
+20241014
+```
 
 ## Dataset Structure
 
@@ -52,4 +81,4 @@ To cite the ELO leaderboard, please use the original citation:
 ```
 
 If you want to cite this repo or specific commits for reproducibility, please
-include a link to this repo and an exact commit hash.
+include a link to this repo and an exact commit hash or tag.