docs: Improve documentation

sketch-core/src/commonMain/kotlin/com/github/panpf/sketch/resize/Precision.kt

@@ -21,21 +21,37 @@ enum class Precision {
 
     /**
      * Try to keep the number of pixels of the returned image smaller than resize. A 10% margin of error is allowed
+     *
+     * * The aspect ratio of the loaded image is the same as the original image
+     * * The number of pixels of the loaded image is less than or slightly greater than resize (10% error)
+     * * The width and height of the loaded image are smaller than or slightly larger than resize
      */
     LESS_PIXELS,
 
     /**
      * The size of the returned image must be smaller than [Resize]
+     *
+     * * The aspect ratio of the loaded image is the same as the original image
+     * * The number of pixels of the loaded image is less than or equal to resize
+     * * The width and height of the loaded image are less than or equal to resize
      */
     SMALLER_SIZE,
 
     /**
      * The size of the new image will not be larger than [Resize], but the aspect ratio will be the same
+     *
+     * * The aspect ratio of the loaded image is different from the original image, but the same as resize
+     * * The number of pixels of the loaded image is less than or equal to resize
+     * * The width and height of the loaded image are less than or equal to resize
      */
     SAME_ASPECT_RATIO,
 
     /**
      * The size of the [Image] returned is exactly the same as [Resize]
+     *
+     * * The aspect ratio of the loaded image is different from the original image, but the same as resize
+     * * The number of image pixels loaded is equal to resize
+     * * The width and height of the loaded image are equal to resize
      */
     EXACTLY,
 }

sketch-core/src/nonAndroidMain/kotlin/com/github/panpf/sketch/util/SystemCallbacks.nonAndroid.kt

@@ -7,7 +7,7 @@ internal actual fun SystemCallbacks(sketch: Sketch): SystemCallbacks = NoopSyste
 
 private class NoopSystemCallbacks : SystemCallbacks {
 
-    // TODO Implement network type detection for non-Android platforms
+    // TODO Implement network type detection for non-Android platforms. https://github.com/jordond/connectivity/blob/main/connectivity-apple/src/appleMain/kotlin/dev/jordond/connectivity/internal/AppleConnectivityProvider.kt
     override val isCellularNetworkConnected get() = false
 
     private val _isShutdown = atomic(false)