Update installation command in README depending on restify version

README.md

@@ -9,6 +9,13 @@ Create Swagger documentation page based on jsdoc
 
 ## Installation
 
+### :warning: Check your restify version
+
+**If you use a restify version prior to v7, you must use the following command:**
+```bash
+npm install restify-swagger-jsdoc@^1 --production
+```
+Else you can use the following command:
 ```bash
 npm install restify-swagger-jsdoc --production
 ```
@@ -43,4 +50,4 @@ The swagger.json file is available at [http://localhost/docs/swagger/swagger.jso
 
 ## How to document the API
 
-This module is based on [swagger-jsdoc](https://www.npmjs.com/package/swagger-jsdoc), so you can refer to this module's documentation to document your API.
+This module is based on [swagger-jsdoc](https://www.npmjs.com/package/swagger-jsdoc), so you can refer to this module's documentation to document your API.