docs: add readme

Author: David Freire

README.md

@@ -0,0 +1,26 @@
+# SQL Shield
+
+Validate raw SQL queries present in your Python codebase against a schema using ```sqlshield```:
+
+```shell
+$ sqlshield --help
+Usage: sqlshield [OPTIONS]
+
+Options:
+  -d, --directory <DIRECTORY>
+          Directory. Defaults to "." (current)
+
+  -s, --schema <SCHEMA>
+          Schema file. Defaults to "schema.sql"
+
+  -h, --help
+          Print help (see a summary with '-h')
+
+  -V, --version
+          Print version
+```
+
+## Similar work
+
+- <https://github.com/andywer/postguard>
+- <https://github.com/schemasafe>