Add initial README for installation

Author: ayufan

README.md

@@ -1,2 +1,90 @@
 # android-7.1
 Main repository with Android 7.1 releases
+
+## Prepare device for flashing
+
+1. Compile and install `rkflashtool`:
+
+```
+git clone https://github.com/ayufan-rock64/rkflashtool
+make -C rkflashtool
+sudo make -C rkflashtool install
+```
+
+1. Connect USB A-to-A cable to upper USB 2.0 port and your computer,
+
+1. Start Rock64 in Loader mode:
+
+  1. Press and hold Recovery Bt
+  2. Press Reset Btn,
+  3. Stop holding Recovery Btn after 3s.
+  
+  To verify device run:
+  
+  ```bash
+  rkflashtool n
+  ...
+  ```
+  
+  You can also start device in Maskrom mode:
+  1. Shorten eMMC PIN,
+  2. Start device.
+
+1. Download and extract one of the releases (without `-update.zip` at end), ex.: https://github.com/ayufan-rock64/android-7.1/releases/download/0.1.0/android-7.1-rock-64-rk3328_box-v0.1.0-r37.zip,
+
+## Install on Linux/OSX
+
+1. Create a installation script:
+
+```bash
+sudo tee /usr/local/bin/rkinstall <<EOF
+#!/bin/bash
+
+set -xe
+
+rkflashtool P < parameter.txt
+for i in uboot trust misc kernel boot recovery system; do
+    rkflashtool w $i < $i.img
+done
+rkflashtool b
+EOF
+
+sudo chmod +x /usr/local/bin/rkinstall
+```
+
+2. Execute script from within directory:
+
+```bash
+$ rkinstall
+```
+
+## Upgrade on Linux/OSX
+
+1. Create upgrade script
+
+```bash
+sudo tee /usr/local/bin/rkupgrade <<EOF
+#!/bin/bash
+
+set -xe
+
+rkflashtool P < parameter.txt
+for i in uboot trust kernel boot recovery system; do
+    rkflashtool w $i < $i.img
+done
+
+rkflashtool b
+EOF
+
+sudo chmod +x /usr/local/bin/rkupgrade
+```
+
+2. Execute upgrade script from within directory:
+
+```bash
+$ rkupgrade
+```
+
+## Author
+
+Kamil Trzciński, 2017, https://ayufan.eu