add install instruction

Signed-off-by: Shengjing Zhu <i@zhsj.me>

README.md

@@ -5,3 +5,49 @@
 This repository contains the kernel modules necessary to run the Anbox
 Android container runtime. They're split out of the original Anbox
 repository to make packaging in various Linux distributions easier.
+
+# Install Instruction
+
+You need to have `dkms` and linux-headers on your system. You can install them by
+`sudo apt install dkms` or `sudo yum install dkms` (`dkms` is available in epel repo
+for CentOS).
+
+Package name for linux-headers varies on different distributions, e.g.
+`linux-headers-generic` (Ubuntu), `linux-headers-amd64` (Debian),
+`kernel-devel` (CentOS, Fedora), `kernel-default-devel` (openSUSE).
+
+* First install the configuration files:
+
+  ```
+  $ sudo cp anbox.conf /etc/modules-load.d/
+  $ sudo cp 99-anbox.rules /lib/udev/rules.d/
+  ```
+
+* Then copy the module sources to `/usr/src/`:
+
+  ```
+  $ sudo cp -rT ashmem /usr/src/anbox-ashmem-1
+  $ sudo cp -rT binder /usr/src/anbox-binder-1
+  ```
+
+* Finally use `dkms` to build and install:
+
+  ```
+  $ sudo dkms install anbox-ashmem/1
+  $ sudo dkms install anbox-binder/1
+  ```
+
+You can verify by loading these modules and checking the created devices:
+
+```
+$ sudo modprobe ashmem_linux
+$ sudo modprobe ashmem_binder
+$ ls -alh /dev/binder /dev/ashmem
+```
+
+You are expected to see output like:
+
+```
+crw-rw-rw- 1 root root  10, 55 Jun 19 16:30 /dev/ashmem
+crw-rw-rw- 1 root root 511,  0 Jun 19 16:30 /dev/binder
+```