Large documentation update (#10)

* Docs: overhaul of all the docs.  The main README.md is much leaner and broke off the steps.  Added a FAQ, greatly expanded the Wiring section.

* Fixed FAQ link

* Fixed some relative links

* Fixed another link

* Minor

* Reverted title of the Project - didn't mean to do that.

docs/backup_firmware.md

@@ -0,0 +1,35 @@
+# Back up the original firmware
+
+Prerequisites:
+- You need the [ESPHome CLI](installing_esphome.md) installed.
+- You need the Vue device to be [wired to a USB to TTY adapter](wiring_and_usb.md).
+
+Reminder: triple check your wiring, making sure you are not connecting +5V to anything other than pin 6.  You can now plug it into your computer and the Vue device should power up and start working as normal.
+
+**1. Determine which USB port it is connected to:**
+  - on Windows, it shows up as `COM3`, `COM4`, etc
+  - on Mac and Linux, look in the filesystem: `/dev/ttyUSB0`, `/dev/ttyUSB1`, or `/dev/tty.usbserial-xxxx`.
+
+**2. To backup the firmware:**
+
+Note: the `esptool` command is used here, which comes installed with the ESPHome CLI.
+```
+# esptool --port <usb_port> --chip esp32 -b 115200 read_flash 0x0 0x400000 <filename>
+```
+
+Examples:
+```
+(on Windows)
+# esptool --port COM3 --chip esp32 -b 115200 read_flash 0x0 0x400000 vue_original_firmare.bin
+
+(on a Mac)
+# esptool --port /dev/tty.usbserial-BG01UJXF --chip esp32 -b 115200 read_flash 0x0 0x400000 vue_original_firmare.bin
+```
+
+Reminder: if it doesn't work, swap pins 1 and 2.
+
+**3. If you need to restore:**
+
+```
+# esptool --port <usb_port> --chip esp32 -b 115200 write_flash --flash_freq 80m 0x0 <filename>
+```