Update README.md (#190)

* Update README.md

* Update README.md

* Update README.md

---------

Co-authored-by: Raphael Mitsch <r.mitsch@outlook.com>

Author: koaning

README.md

@@ -994,7 +994,8 @@ by setting the environmental variable `HF_HOME`.
 
 Interacting with LLMs, either through an external API or a local instance, is costly.
 Since developing an NLP pipeline generally means a lot of exploration and prototyping,
-`spacy-llm` implements a built-in cache to avoid reprocessing the same documents at each run.
+`spacy-llm` implements a built-in cache to avoid reprocessing the same documents at each run
+that keeps batches of documents stored on disk.
 
 Example config block:
 
@@ -1006,11 +1007,14 @@ batch_size = 64
 max_batches_in_mem = 4
 ```
 
-| Argument             | Type                         | Default | Description                                          |
-| -------------------- | ---------------------------- | ------- | ---------------------------------------------------- |
-| `path`               | `Optional[Union[str, Path]]` | `None`  | Cache directory. If `None`, no caching is performed. |
-| `batch_size`         | `int`                        | 64      | Number of docs in one batch (file).                  |
-| `max_batches_in_mem` | `int`                        | 4       | Max. number of batches to hold in memory.            |
+| Argument             | Type                         | Default | Description                                                                                                               |
+| -------------------- | ---------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------- |
+| `path`               | `Optional[Union[str, Path]]` | `None`  | Cache directory. If `None`, no caching is performed, and this component will act as a NoOp.                               |
+| `batch_size`         | `int`                        | 64      | Number of docs in one batch (file). Once a batch is full, it will be peristed to disk.                                    |
+| `max_batches_in_mem` | `int`                        | 4       | Max. number of batches to hold in memory. Allows you to limit the effect on your memory if you're handling a lot of docs. |
+
+When retrieving a document, the `BatchCache` will first figure out what batch the document belongs to. If the batch
+isn't in memory it will try to load the batch from disk and then move it into memory. 
 
 Note that since the cache is generated by a registered function, you can also provide your own registered function
 returning your own cache implementation. If you wish to do so, ensure that your cache object adheres to the