add: example command in README

README.md

@@ -10,6 +10,79 @@ go install github.com/GoFarsi/gvm@latest
 
 2. install from [release page](https://github.com/GoFarsi/gvm/releases).
 
+# Example
+example commands of gvm tool
+### install
+install latest version of Go
+```shell
+gvm install
+```
+install with backup downloaded Go compiler
+```shell
+gvm install -b /home/{user}
+```
+install specific version of Go compiler
+```shell
+gvm install -v 1.19.3
+```
+
+### upgrade
+upgrade to latest version Go
+```shell
+gvm upgrade
+```
+upgrade with backup downloaded Go compiler
+```shell
+gvm upgrade -b /home/{user}
+```
+upgrade to specific version of Go compiler
+```shell
+gvm upgrade -v 1.19.3
+```
+
+### downgrade
+downgrade to previous version of Go
+```shell
+gvm downgrade
+```
+downgrade with backup downloaded Go compiler
+```shell
+gvm downgrade -b /home/{user}
+```
+downgrade to specific version of Go compiler
+```shell
+gvm upgrade -v 1.19.2
+```
+
+### list
+list of version with commit id Go compiler
+```shell
+gvm list
+```
+list of version with commit id Go compiler in 10 line
+```shell
+gvm list -l 10
+```
+
+### release
+show release note link all version of Go compiler
+```shell
+gvm release
+```
+show release note specific of version Go compiler
+```shell
+gvm release -v 1.19
+```
+
+### notification
+check new version of Go compiler base on your installed version
+```shell
+gvm notification
+```
+**note**:
+> you can set cronjob for check new version Go compiler using command :
+> `(crontab -l ; echo "* */6 * * * bash gvm notification >/dev/null 2>&1")| crontab -` every 6 hours.
+
 # TODO
 - [x] gvm for linux
 - [ ] mac os