Re-write net docs

docs/net/diff.md

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+# Diff
+
+Efficient event synchronization using NIP-77 Negentropy protocol.
+
+## Core Classes
+
+### `Difference`
+
+Handles negentropy synchronization with a single relay for a single filter.
+
+**Events:**
+- `DifferenceEvent.Message` - Emitted with `{have, need}` arrays and relay URL
+- `DifferenceEvent.Error` - Emitted when sync fails
+- `DifferenceEvent.Close` - Emitted when sync completes
+
+**Methods:**
+- `close()` - Stop synchronization and cleanup
+
+## Functions
+
+### `diff(options)`
+
+Check what events each relay has or needs compared to local events.
+
+**Returns:** Array of `{relay, have, need}` objects - `have` are events the relay has that you don't, `need` are events you have that the relay doesn't.
+
+### `pull(options)`
+
+Fetch missing events after comparing with relays.
+
+**Returns:** Array of retrieved events.
+
+### `push(options)`
+
+Publish local events that relays are missing.
+
+## Example
+
+```typescript
+// Check what events each relay has/needs
+const results = await diff({
+  relays: ['wss://relay1.com', 'wss://relay2.com'],
+  filters: [{kinds: [1], authors: ['pubkey...']}],
+  events: localEvents
+})
+
+// Pull events that relays have but we don't
+const newEvents = await pull({
+  relays: ['wss://relay1.com'],
+  filters: [{kinds: [1]}],
+  events: localEvents
+})
+```