Merge pull request #6 from HEPData/readme-usage-section

Readme usage section

README.md

@@ -13,6 +13,53 @@ submissions hold. Its evolution is coupled with the [hepdata-pyhf-visualizer][py
 JS package, as this one renders what gets summarized by this component.
 
 
+## Installation
+
+Via pip:
+```sh
+pip install hepdata-pyhf-extractor
+```
+
+Via GitHub (for developers):
+```
+git clone https://github.com/HEPData/hepdata-pyhf-extractor
+cd hepdata-pyhf-extractor
+pip install ".[dev]"
+```
+
+
+## Usage
+
+To extract basic information out of a `pyhf` Pallet file, the summarizers can:
+
+A) Receive a Pallet file path for them to open and read it internally.
+```python3
+from pyhf_extractor import V1PalletSummarizer
+
+# The provided file can be either .json.gz or .json
+pallet_path = "example_pallet.json.gz"
+pallet_path = "example_pallet.json"
+
+summarizer = V1PalletSummarizer(pallet_path=pallet_path)
+summary = summarizer.summarize()
+```
+
+B) Receive an already parsed Pallet file:
+```python3
+import gzip
+import json
+from pyhf_extractor import V1PalletSummarizer
+
+pallet_path = "example_pallet.json.gz"
+
+with gzip.open(pallet_path) as file:
+    pallet_data = json.load(file)           
+
+summarizer = V1PalletSummarizer(pallet_data=pallet_data)
+summary = summarizer.summarize()
+```
+
+
 ## Development
 The package uses [Black][black-web], in addition to [pre-commit][pre-commit-web] to control its style.
 
@@ -26,16 +73,14 @@ To check for style inconsistencies:
 make check
 ```
 
-
-## Testing
+### Testing
 The package uses [pytest][pytest-web] to run all the tests:
 
 ```sh
 make test
 ```
 
-
-## Release version
+### Release version
 To bump and tag a particular commit to mark a release:
 
 ```sh