📝 Polish onboarding and add feature examples

examples/file_rotation/main.mbt

@@ -0,0 +1,19 @@
+fn main {
+  if !@lib.native_files_supported() {
+    println("native file sink is not available on this backend")
+    return
+  }
+
+  let logger = @lib.Logger::new(
+    @lib.file_sink(
+      "bitlogger-example.log",
+      auto_flush=true,
+      rotation=Some(@lib.file_rotation(128, max_backups=2)),
+    ),
+    min_level=@lib.Level::Info,
+    target="demo.file",
+  )
+  logger.info("file rotation ready", fields=[@lib.field("kind", "file")])
+  ignore(logger.sink.flush())
+  ignore(logger.sink.close())
+}

examples/file_rotation/moon.pkg

@@ -0,0 +1,7 @@
+import {
+  "Nanaloveyuki/BitLogger/src" @lib,
+}
+
+options(
+  "is-main": true,
+)