Fix handbook manifest

Author: swissspidy

bin/handbook-manifest.json

@@ -8,8 +8,8 @@
     "behat-steps": {
         "title": "Behat Steps",
         "slug": "behat-steps",
-        "markdown_source": "https:\/\/github.com\/wp-cli\/handbook\/blob\/main\/behat-steps.md",
-        "parent": null
+        "markdown_source": "https:\/\/github.com\/wp-cli\/handbook\/blob\/main\/references\/behat-steps.md",
+        "parent": "references"
     },
     "bug-reports": {
         "title": "Bug Reports",
@@ -368,8 +368,8 @@
     "internal-api": {
         "title": "Internal API",
         "slug": "internal-api",
-        "markdown_source": "https:\/\/github.com\/wp-cli\/handbook\/blob\/main\/internal-api.md",
-        "parent": null
+        "markdown_source": "https:\/\/github.com\/wp-cli\/handbook\/blob\/main\/references\/internal-api.md",
+        "parent": "references"
     },
     "philosophy": {
         "title": "Philosophy",