added hook_help()

Added hook_help() for developers to get access for Drupal help pages and info of the module. Please review the changes done on .moudle file

csp.module

@@ -4,3 +4,25 @@
  * @file
  * Contains csp.module.
  */
+
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Implements hook_help().
+ */
+function csp_help($route_name, RouteMatchInterface $route_match) {
+  switch ($route_name) {
+    case 'help.page.csp':
+      $content = '';
+      $content .= '<h3>' . t('About Content-Security-Policy module') . '</h3>';
+      $content .= '<p>' . t('The Content-Security-Policy module provides an interface for configuring the Content Security Policy (CSP) HTTP response header.') . '</p>';
+      $content .= '<h4>' . t('What is CSP?') . '</h4>';
+      $content .= '<p>' . t('Content Security Policy (CSP) is an added layer of security that helps to detect and mitigate certain types of attacks, including Cross Site Scripting (XSS) and data injection attacks.') . '</p>';
+      $content .= '<p>' . t('CSP works by defining a set of rules that specify which types of content are allowed to be loaded on a web page.') . '</p>';
+      $content .= '<h4>' . t('How to configure CSP with this module?') . '</h4>';
+      $content .= '<p>' . t('The Content-Security-Policy module provides an easy-to-use interface for configuring the CSP header. Simply navigate to the configuration page at /admin/config/system/csp, and use the provided form to configure your desired CSP policy.') . '</p>';
+
+      return ['#markup' => $content];
+
+  }
+}