Update Raspberry Pi image

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README.md

@@ -5,8 +5,9 @@
 
 This is the base Nerves System configuration for the Raspberry Pi 4 Model B.
 
-![Fritzing Raspberry Pi 4 image](assets/images/raspberry-pi-3-model-b.png)
-<br><sup>[Image credit](#fritzing)</sup>
+![Raspberry Pi 4 image](assets/images/raspberry-pi-4-model-b.jpg)
+<br><sup>[Michael Henzler / Wikimedia Commons / CC BY-SA
+4.0](https://en.wikipedia.org/wiki/File:Raspberry_Pi_4_Model_B_-_Top.jpg)</sup>
 
 | Feature              | Description                     |
 | -------------------- | ------------------------------- |
@@ -130,73 +131,5 @@ take versions of the repositories that have similar commit times.
 
 The Linux kernel compiled for Nerves is a stripped down version of the default
 Raspberry Pi Linux kernel. This is done to remove unnecessary features, select
-some Nerves-specific features, and to save space. To reproduce the kernel
-configuration found here, do the following (this is somewhat tedious):
-
-1. Start with `arch/arm/configs/bcmrpi_defconfig`. This is the kernel
-   configuration used in the official Raspberry Pi images.
-1. Turn off all filesystems except for `f2fs`, `squashfs`, `tmpfs`, `proc`,
-   `sysfs`, and `vfat`. Squashfs only needs ZLIB support.
-1. `vfat` needs to default to `utf8`. Enable native language support for
-   `ascii`, `utf-8`, `ISO 8859-1`, codepage 437, and codepage 850.
-1. Disable all network drivers and wireless LAN drivers except for Broadcom
-   FullMAC WLAN.
-1. Disable PPP and SLIP
-1. Disable the WiFi drivers in the Staging drivers menus
-1. Disable TV, AM/FM, Media USB adapters, DVB Frontends and Remote controller
-   support in the Multimedia support menus.
-1. Go to `Device Drivers->Sound card support`. Disable `USB sound devices` in
-   ALSA. Disable `Open Sound System`.
-1. Go to `Device Drivers->Graphics support`. Disable `DisplayLink`
-1. In `Kernel Features`, select `Preemptible Kernel (Low-Latency Desktop)`,
-   disable the memory allocator for compressed pages.
-1. In `Userspace binary formats`, disable support for MISC binaries.
-1. In `Networking support`, disable Amateur Radio support, CAN bus subsystem,
-   IrDA subsystem, Bluetooth, WiMAX, Plan 9, and NFC. (TBD - this may be too
-   harsh, please open issues if you're using any of these and it's the only
-   reason for you to create a custom system.)
-1. In `Networking options`, disable IPsec, SCTP, Asynchronous Transfer Mode,
-   802.1d Ethernet Bridging, L2TP, VLAN, Appletalk, 6LoWPAN, 802.15.4, DNS
-   Resolver, B.A.T.M.A.N, Open vSwitch, MPLS, and the Packet Generator in Network
-   testing.
-1. In `Networking support->Wireless`, enable "use statically compiled regulatory
-   rules database". Build in `cfg80211` and `mac80211`. Turn off `mac80211` mesh
-   networking and LED triggers. Turn off `cfg80211` wireless extensions
-   compatibility.
-1. In `Kernel hacking`, disable KGDB, and Magic SysRq key.
-1. In Device Drivers, disable MTD support. In Block devices, disable everything
-   but Loopback and RAM block device. Disable RAID and LVM.
-1. In `Enable the block layer`, deselect everything but the PC BIOS partition
-   type (i.e., no Mac partition support, etc.).
-1. In `Enable loadable module support`, select "Trim unused exported kernel
-   symbols". NOTE: If you're having trouble with an out-of-tree kernel module
-   build, try deslecting this!!
-1. In `General Setup`, turn off `initramfs/initfd` support, Kernel .config
-   support, OProfile.
-1. In `Device Drivers -> I2C -> Hardware Bus Support` compile the module into
-   the kernel and disable everything but `BCM2708 BSC` support.
-1. In `Device Drivers -> SPI` compile in the BCM2835 SPI controller and User
-   mode SPI device driver support.
-1. In `Device Drivers -> Staging` disable `Support for small TFT LCD modules`
-1. In `Device Drivers -> Dallas's 1-wire support`, disable everything but the
-   GPIO 1-Wire master and the thermometer slave. (NOTE: Why is the thermometer
-   compiled in? This seems historical.)
-1. Disable `Hardware Monitoring support`, `Sonics Silicon Backplane support`
-1. In `Device Drivers -> Character devices -> Serial drivers`, disable 8250 and
-   SC16IS7xx support. Disable the RAW driver.
-1. In `Networking support->Network options`, disable `IP: kernel level
-   autoconfiguration`
-1. In `Networking support->Network options->TCP: advanced congestion control`
-   disable everything except for `CUBIC TCP`.
-1. Disable `Real Time Clock`.
-1. Disable everything in `Cryptographic API` and `Library routines` that can be
-   disabled. Sometimes you need to make multiple passes.
-1. Disable EEPROM 93CX6 support, PPS support, all GPIO expanders, Speakup core,
-   Media staging drivers, STMicroelectronics STMPE, anything "Wolfson".
-1. Disable most ALSA for SoC audio support and codecs. NOTE: We probably should
-   support a few, but I have no clue which ones are most relevant and there are
-   tons of device drivers in the list.
-1. Disable IIO and UIO.
-1. Disable NXP PCA9685 PWM driver
-
-[Image credit](#fritzing): This image is from the [Fritzing](http://fritzing.org/home/) parts library.
+some Nerves-specific features like F2FS and SquashFS support, and to save space.
+