docs: add ktx/crashlytics.md to .opensource/project.json
"pages": {
"README.md": "Development Guide",
"docs/ktx/common.md": "Common KTX",
+ "docs/ktx/crashlytics.md": "Crashlytics KTX",
"docs/ktx/dynamic-links.md": "Dynamic Links KTX",
"docs/ktx/firestore.md": "Firestore KTX",
"docs/ktx/functions.md": "Functions KTX",
