Update README.md (#13)

### Description
<!---Why are we making this change? What does it do?--->
marginally more doc
### Testing
<!---How was this tested?--->

### Impact
<!---What components does this impact? How can it affect prod?--->

### Other
<!---What else can this impact? What special considerations are needed
when reviewing the PR?--->


![image](https://github.com/user-attachments/assets/bafd3f28-88dd-44b8-a6e5-b992abe2b668)

Author: echavemann

README.md

@@ -1,18 +1,23 @@
 # lens
 
-
 NUFT's data fetching from internal servers solution
 
 
-Only supporting Python 3.12 for now. Heavily in progress, more versions and whatnot soon.
-
-
 ## Usage
 Lens provides a simple data fetching API. All queries require `startup` to be called on the instance before fetching.
 
+Startup validates the selected project root (or default: `/pool/lens`).
+Specific information on the contents of a data directory can be viewed in that directory's `metadata.json`.
+A complete example of the file layout is available in either `file_structure.md` (tree) or `test/testing_data`.
 
 ```python
 ln = Lens()
 ln.startup()
 df = ln.load_trades_for_day("avax", "2025-02-21")
+df = ln.load_depth_for_day("avax", "2025-02-21")
 ```
+
+These are the only two queries currently available, and both return `pd.DataFrame`. Headers are included.
+
+`main.py` is included as a quick way to run the startup checks without needing to integrate with another codebase.
+