doc(readme): add basic info about the validator

Signed-off-by: Jefersson Nathan <malukenho.dev@gmail.com>

README.md

@@ -0,0 +1,40 @@
+📚 Xulieta - SQL Validator
+==========================
+
+> **Warning**
+> This library is highly experimental.
+
+#### 📊 SQL Validator?
+
+Yes, you read it right. This packages provides basic SQL validation for.
+your code snippets Just plug it in your xulieta configuration and you
+are good to go.
+
+```shell script
+composer require codelicia/xulieta-sql-validator --dev
+```
+
+Xulieta will automatically detect the validator and will configure it
+for you. You can check it out on you `.xulieta.xml` file.
+
+---
+
+### Checking for errors
+
+After registering the validator, no extra steps are required. Just run
+xulieta as usual.
+
+ ```shell script
+ ./vendor/bin/xulieta check:erromeu <directory>
+ ```
+
+### How to use it on my docs?
+
+Just make sure you mark you code block as `sql`, `mysql` or
+`postgresql` and you are good to go If you'd like to add something
+else, please open an issue or a PR.
+
+## Author 🎩✨
+
+- malukenho (@malukenho)
+- Eher (@EHER)