update readme

Author: ingbyr

readme.md

@@ -0,0 +1,93 @@
+## gohost
+
+Gohost is a simple host switcher tool supporting Linux, macOS and Windows.
+
+**To modify the system host file gohost need running in admin mode, such as `sudo gohost` in Linux and macOS
+or `Admin CMD` in Windows.**
+
+## Usage
+
+### And new host file
+
+`gohost new HOST_NAME GROUP_NAME_1 GROUP_NAME_2 ... `
+
+For example
+
+```shell
+# create a devHost host file which belongs to dev1 and dev2 group
+> gohost new devHost dev1 dev2
+```
+
+### Edit existed host file
+> Make sure `vim` is in system PATH
+
+`gohost edit HOST_NAME`
+
+
+### Delete existed host file
+
+`gohost rm HOST_NAME`
+
+
+### List host
+
+`gohost ls [-a]`
+
+For example
+
+```shell
+# List host group
+> gohost ls
++-------+---------+
+| GROUP |  HOSTS  |
++-------+---------+
+| dev1  | devHost |
+| dev2  | devHost |
++-------+---------+
+
+# List host
+> gohost ls -a
++---------+------------+
+|  HOST   |   GROUPS   |
++---------+------------+
+| devHost | dev1, dev2 |
++---------+------------+
+
+```
+
+
+### Add group to existed host
+
+`gohost cg HOST_NAME [ -a | -d ] GROUP_NAME_1,GROUP_NAME_2...`
+
+For example
+
+```shell
+# add group dev3, dev4 for devHost
+> gohost cg devHost -a dev3,dev4
+added groups 'dev3, dev4'
++---------+------------------------+
+|  HOST   |         GROUPS         |
++---------+------------------------+
+| devHost | dev1, dev2, dev3, dev4 |
++---------+------------------------+
+
+# remove group dev1 for devHost
+> gohost cg devHost -d dev1
+removed groups 'dev1'
++---------+------------------+
+|  HOST   |      GROUPS      |
++---------+------------------+
+| devHost | dev2, dev3, dev4 |
++---------+------------------+
+```
+
+
+### Use group host as system host
+
+`gohost use GROUP_NAME`
+
+
+### Display current system host
+
+`gohost sys`