Updated README

README.md

@@ -1,2 +1,35 @@
-# data_harvest
-Stock data harvesting modules
+# Rust Finance Data Harvest Library
+
+[![License](https://img.shields.io/github/license/felipet/lacoctelera_backend?style=flat-square)](https://github.com/felipet/lacoctelera_backend/blob/main/LICENSE)
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+
+This library includes several modules that extract finance and stock related data from web sites. The main purpose
+of the library is to retrieve useful data for financial quantitative analysis, and organise it into a data base.
+
+## Supported Sources of Data
+
+At the moment the following sources of data are supported:
+
+### [Comisión Nacional de Valores](https://www.cnmv.es)
+The CNMV is the Spanish stock exchange supervisor and regulator. Its web site includes many useful registers,
+though the access is complicated due to the organisation of the web site, and certainly not friendly for
+machines.
+The library supports extracting data about [short positions](https://www.cnmv.es/portal/consultas/busqueda?id=29)
+against companies listed in the IBEX35.
+
+#### Short Data Provider
+
+This `struct` [web_scrappers::CnmvProvider] includes logic to extract the active short positions against a
+given company of the IBEX35. The module works together with the API defined in the
+[Finance Lib](https://crates.io/crates/finance_api) crate, and uses the implementation of such API
+[Finance Ibex](https://crates.io/crates/finance_ibex). So have a look at them before using this module.
+
+## API
+There is no defined API of this library because the main goal of the library is to keep a private data base with
+all the harvested data. Hence if you just need to scrap data from a supported web site, look for any of the
+modules within [web_scrappers].
+
+## Data Base Management
+The modules within [feeders] are meant to call modules that produce data and push the new data to the private
+data base.
+