After updating Firefox, by default it display's a "What's New" page.
If you enable this policy, that page will be supressed.
| Registry Hive | HKEY_LOCAL_MACHINE |
| Registry Path | Software\Policies\Mozilla\Firefox |
| Value Name | SupressUpdatePage |
| Value Type | REG_DWORD |
| Enabled Value | 1 |
| Disabled Value | 0 |