docs: Update README

README.md

@@ -1,3 +1,41 @@
 # zpinner
 
 Nice zpinner in the terminal made in zig.
+
+## Usage
+```zig
+const std = @import("std");
+const zpinner = @import("zpinner.zig");
+
+pub fn main() !void {
+    const stdout_file = std.io.getStdOut().writer();
+    var zpin = zpinner.new(stdout_file.any(), .{});
+    zpin.set_indicator(zpinner.Moon);
+    zpin.set_suffix(" calculating route to the moon");
+    try zpin.start();
+    std.time.sleep(5 * std.time.ns_per_s);
+    try zpin.stop();
+    zpin.set_suffix(" counting snakes");
+    zpin.set_indicator(zpinner.Snake);
+    try zpin.start();
+    std.time.sleep(5 * std.time.ns_per_s);
+    zpin.set_indicator(zpinner.Earth);
+    zpin.set_suffix(" calculating route back to earth");
+    std.time.sleep(5 * std.time.ns_per_s);
+    try zpin.stop();
+    zpin.set_suffix(" calculating next week weather");
+    zpin.set_indicator(zpinner.Weather);
+    try zpin.start();
+    std.time.sleep(5 * std.time.ns_per_s);
+    try zpin.stop();
+    zpin.set_suffix(" ZzZzz...");
+    zpin.set_indicator(zpinner.Clock);
+    try zpin.start();
+    std.time.sleep(5 * std.time.ns_per_s);
+    try zpin.stop();
+
+    try stdout_file.print("work done\n", .{});
+}
+```
+
+