document the redirect component

Author: lovasoa

examples/official-site/sqlpage/migrations/09_redirect.sql

@@ -0,0 +1,44 @@
+INSERT INTO component (name, description, icon, introduced_in_version)
+VALUES (
+        'redirect',
+        'Redirects the user to another page.
+        This component is useful for implementing redirects after a form submission,
+        or to redirect users to a login page if they are not logged in.
+        
+        Contrary to the http_header component, this component completely stops the execution of the page after it is called,
+        so it is suitable to use to hide sensitive information from users that are not logged in, for example.
+
+        Since it uses an HTTP header to redirect the user, it is not possible to use this component after the page has started being sent to the browser.',
+        'arrow-right',
+        '0.7.2'
+    );
+-- Insert the parameters for the http_header component into the parameter table
+INSERT INTO parameter (
+        component,
+        name,
+        description,
+        type,
+        top_level,
+        optional
+    )
+VALUES (
+        'redirect',
+        'link',
+        'The URL to redirect the user to.',
+        'TEXT',
+        TRUE,
+        FALSE
+    );
+-- Insert an example usage of the http_header component into the example table
+INSERT INTO example (component, description)
+VALUES (
+        'redirect',
+        '
+Redirect an user to the login page if they are not logged in:
+
+```sql
+SELECT ''redirect'' AS component, ''login.sql'' AS link
+WHERE NOT EXISTS (SELECT 1 FROM login_session WHERE id = sqlpage.cookie(''session_id''));
+```
+'
+    );