Add some class documentation for HardwareShortcutsSpec

zoomable/src/commonMain/kotlin/me/saket/telephoto/zoomable/HardwareShortcutsSpec.kt

@@ -1,8 +1,27 @@
 package me.saket.telephoto.zoomable
 
 import androidx.compose.runtime.Immutable
+import androidx.compose.ui.focus.FocusRequester
 import dev.drewhamilton.poko.Poko
 
+/**
+ * Describes how keyboard and mouse shortcuts are handled. When [enabled], [Modifier.zoomable][zoomable]'s
+ * content will participate in the focus system to receive hardware events.
+ *
+ * Keep in mind that hardware shortcuts will not work until your zoomable content is focused.
+ * To do this automatically, use a [FocusRequester]:
+ *
+ * ```
+ * val focusRequester = remember { FocusRequester() }
+ * LaunchedEffect(Unit) {
+ *   focusRequester.requestFocus()
+ * }
+ *
+ * ZoomableImage(
+ *   modifier = Modifier.focusRequester(focusRequester),
+ * )
+ * ```
+ */
 @Poko
 @Immutable
 class HardwareShortcutsSpec(