[DO] Note on nominal metadata when writing to SQLite DO (#20217)

* Adding note on storing metadata when writing to
SQLite-backed DO.

* Wording clarification

* Implementing PCX review feedback.

* Turning the caution note into FAQ section.

* Clarifying language on empty database and nominal metadata.

* Splitting question into 2 for clearer framing.

Author: Oxyjun

src/content/docs/durable-objects/platform/limits.mdx

@@ -44,7 +44,9 @@ For Durable Object classes with [SQLite storage backend](/durable-objects/best-p
 
 <Render file="limits_increase" product="workers" />
 
-## How much work can a single Durable Object do?
+## Frequently Asked Questions
+
+### How much work can a single Durable Object do?
 
 Durable Objects can scale horizontally across many Durable Objects. Each individual Object is inherently single-threaded.
 
@@ -54,7 +56,7 @@ Durable Objects can scale horizontally across many Durable Objects. Each individ
 
 A Durable Object that receives too many requests will, after attempting to queue them, return an [overloaded](/durable-objects/observability/troubleshooting/#durable-object-is-overloaded) error to the caller.
 
-## How many Durable Objects can I create?
+### How many Durable Objects can I create?
 
 Durable Objects are designed such that the number of individual objects in the system do not need to be limited, and can scale horizontally.
 

src/content/docs/durable-objects/platform/pricing.mdx

@@ -118,3 +118,15 @@ In this scenario, the estimated monthly cost would be calculated as:
 ## Storage API billing
 
 <Render file="storage_api_pricing" product="workers" />
+
+## Frequently Asked Questions
+
+### Does an empty table / SQLite database contribute to my storage?
+
+Yes, although minimal. Empty tables can consume at least a few kilobytes, based on the number of columns (table width) in the table. An empty SQLite database consumes approximately 12 KB of storage.
+
+### Does metadata stored in Durable Objects count towards my storage?
+
+All writes to a SQLite-backed Durable Object stores nominal amounts of metadata in internal tables in the Durable Object, which counts towards your billable storage.
+
+The metadata remains in the Durable Object until you call [`deleteAll()`](/durable-objects/api/storage-api/#deleteall).