Fix SQLAlchemy link

This is RST, not Markdown.

Author: StevenMaude

README

@@ -33,7 +33,7 @@ Helper functions for saving and querying an SQL database. Updates
 the schema automatically according to the data you save.
 
 Currently only supports SQLite. It will make a local SQLite database.
-It is based on [SQLAlchemy](https://pypi.python.org/pypi/SQLAlchemy).
+It is based on `SQLAlchemy <https://pypi.python.org/pypi/SQLAlchemy>`_.
 You should expect it to support other SQL databases at a later date.
 
 scraperwiki.sql.save(unique_keys, data[, table_name="swdata"])