Change "@" for "$" as dynamic var identifier

README.md

@@ -229,7 +229,17 @@ Result:  'abc'
 
 #### Dynamic variables
 
-If you prefix a variable with `@`, then the variable is considered a dynamic variable. The value after the @-synbol will be treated as a command and the output assigned.
+If you prefix a variable with `$`, then the variable is considered a dynamic
+variable. The value after the $-symbol will be treated as a command and the
+output assigned.
+
+```yml
+build:
+  cmds:
+    - go build -ldflags="-X main.Version={{.LAST_GIT_COMMIT}}" main.go
+  vars:
+    LAST_GIT_COMMIT: $git log -n 1 --format=%h
+```
 
 ### Go's template engine
 

variable_handling.go

@@ -23,7 +23,7 @@ func handleDynamicVariableContent(value string) (string, error) {
 	if value == "" {
 		return value, nil
 	}
-	if value[0] != '@' {
+	if value[0] != '$' {
 		return value, nil
 	}
 	var cmd *exec.Cmd