Add how to install in JetBrains (#56)

* Add how to install in JetBrains

Signed-off-by: Yu ISHIKAWA <[email protected]>

* Add example screenshot and small text tweaks

* forgot a slash

---------

Signed-off-by: Yu ISHIKAWA <[email protected]>
Co-authored-by: Joel Labes <[email protected]>

README.md

@@ -77,6 +77,36 @@ This repository contains schemata for:
 }
 ```
 
+## Installation in JetBrains
+
+IDEs by JetBrains like PyCharm and IntelliJ enable us to use the JSON Schema, using [the JSON schema mapping feature](https://www.jetbrains.com/help/idea/json.html#ws_json_schema_add_custom).
+
+1. Open the preferences of JSON schema mapping in JetBrains
+2. Add custom schema mappings
+
+There is no way to add the preferences with a configuration file like VS Code.
+As we have to manually configure them one by one, we just describe values of the configurations below.
+If you want to know the details, the [dbt YAML validator in JetBrains article](https://yu-ishikawa.medium.com/dbt-yaml-validator-in-jetbrains-b5ef25e9253e) describes how to configure the JSON schema mapping in details.
+
+- Project definition files
+    - URL: `https://raw.githubusercontent.com/dbt-labs/dbt-jsonschema/main/schemas/dbt_project.json`
+    - Schema version: JSON schema version 7
+    - Mapping: `dbt_project.yml`
+- Package files
+    - URL: `https://raw.githubusercontent.com/dbt-labs/dbt-jsonschema/main/schemas/packages.json`
+    - Schema version: JSON schema version 7
+    - Mapping: `packages.yml`
+- Selectors files
+    - URL: `https://raw.githubusercontent.com/dbt-labs/dbt-jsonschema/main/schemas/selector.json`
+    - Schema version: JSON schema version 7
+    - Mapping: `selector.yml`
+- Property files
+    - URL: `https://raw.githubusercontent.com/dbt-labs/dbt-jsonschema/main/schemas/dbt_yml_files.json`
+    - Schema version: JSON schema version 7
+    - Mapping: `models/**/*.yml`, `analysis/**/*.yml`, `snapshots/**/*.yml`
+
+![A screenshot of a JetBrains Preferences panel showing the correct mapping of the dbt_yml_files JSON Schema](/jetbrains-config.png)
+
 _Do you use a different IDE which also supports JSON Schema? Please open a PR with setup instructions and links to any extensions!_
 
 ## Contributing