docs: android limits

Author: Krzysztof Borowy

website/docs/Limits.md

@@ -0,0 +1,17 @@
+---
+id: limits
+title: Known storage limits
+sidebar_label: Known limits
+---
+
+## Android
+
+AsyncStorage for Android uses SQLite for storage backend. While it has [its own size limits](https://www.sqlite.org/limits.html), Android system also have two known limits: total storage size and per-entry size limit.
+
+
+- Total storage size is capped at 6 MB by default. You can increase this size by [specifying a new size using feature flag.](advanced/IncreaseDbSize.md) 
+
+- Per-entry is limited by a size of a WindowCursor, a buffer used to read data from SQLite. [Currently it's size is around 2 MB](https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/res/res/values/config.xml;l=2103).
+  This means that the single item read at one time cannot be larger than 2 MB. There's no supported workaround from AsyncStorage. 
+  We suggest keeping your data lower than that, by chopping it down into many entries, instead of one massive entry.
+  This is where [`multiGet`](API.md#multiget) and [`multiSet`](API.md#multiset) APIs can shine.

website/sidebars.js

@@ -1,6 +1,6 @@
 module.exports = {
   docs: {
-    'Getting started': ['install', 'usage', 'link', 'api'],
+    'Getting started': ['install', 'usage', 'link', 'api', 'limits'],
     Advanced: ['advanced/next', 'advanced/jest', 'advanced/brownfield', 'advanced/backup', 'advanced/executor', 'advanced/db_size'],
     Debugging: ['debugging/communityPackages'],
     Help: ['help/troubleshooting'],