Add detailed documentation in README.md for setup and usage

readme.md

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+# Simple Persistence for Kotlin
+
+A lightweight, file-based persistence library for Kotlin applications that provides a simple way to store, retrieve, and query objects.
+
+## Available on Maven Central
+
+```kotlin
+// Gradle Kotlin DSL
+implementation("nl.astraeus:simple-persistence-kotlin:1.1.5")
+```
+
+```groovy
+// Gradle Groovy DSL
+implementation 'nl.astraeus:simple-persistence-kotlin:1.1.5'
+```
+
+```xml
+<!-- Maven -->
+<dependency>
+    <groupId>nl.astraeus</groupId>
+    <artifactId>simple-persistence-kotlin</artifactId>
+    <version>1.1.5</version>
+</dependency>
+```
+
+## Features
+
+- Simple and intuitive API for persisting Kotlin objects
+- Transaction support with ACID properties
+- Optimistic locking to handle concurrent modifications
+- Flexible indexing for efficient querying
+- Object references and collections handling
+- Encryption support for sensitive data
+- Snapshot and transaction log capabilities
+- File-based storage with automatic cleanup
+
+## Quick Start
+
+### Define your model
+
+```kotlin
+class Person(
+  override var id: Long = 0,
+  override var version: Long = 0,
+  val name: String,
+  val age: Int,
+  company: Company? = null
+) : Persistable, Cloneable {
+  var company: Company? by nullableReference(company)
+
+  companion object {
+    private const val serialVersionUID: Long = 1L
+  }
+}
+
+class Company(
+  override var id: Long = 0,
+  override var version: Long = 0,
+  val name: String
+) : Persistable, Cloneable {
+  val persons: MutableCollection<Person> = referenceCollection()
+
+  companion object {
+    private const val serialVersionUID: Long = 1L
+  }
+}
+```
+
+### Initialize the persistence manager
+
+```kotlin
+val persistent = Persistent(
+  directory = File("data", "my-app"),
+  indexes = arrayOf(
+    index<Person>("name") { p -> (p as? Person)?.name ?: "" },
+    index<Person>("age") { p -> (p as? Person)?.age ?: -1 },
+    index<Company>("name") { p -> (p as? Company)?.name ?: "" }
+  )
+)
+```
+
+### Perform CRUD operations
+
+```kotlin
+// Create or update
+persistent.transaction {
+  val person = Person(
+    id = 1L,
+    name = "John Doe",
+    age = 30
+  )
+
+  val company = Company(
+    id = 1L,
+    name = "ACME Inc."
+  )
+
+  person.company = company
+  company.persons.add(person)
+
+  store(person)
+  store(company)
+}
+
+// Read
+persistent.query {
+  val person = find<Person>(1L)
+  println("Found person: $person")
+
+  // Query by index
+  val persons: List<Person> = findByIndex("age", 30)
+
+  // Search with predicate
+  val results = search(Person::class) { p -> p.name.startsWith("John") }
+}
+
+// Delete
+persistent.transaction {
+  val person = find<Person>(1L)
+  if (person != null) {
+    delete(person)
+  }
+}
+```
+
+## How it works
+
+- In-memory model: Your objects live in memory during normal operation for fast reads and writes.
+- Durable writes: Every create/update/delete inside a transaction is appended to on-disk transaction log files (*.trn). This is a write-ahead log approach.
+- Startup recovery: On application startup, the library replays the transaction logs (and any snapshot, if present) to rebuild the in-memory model.
+- Snapshots: You can create a compact on-disk snapshot (*.snp) of the current in-memory state. On the next startup, the snapshot is loaded first and only the newer transaction log files are replayed. This keeps startup time low without losing durability.
+
+Tip: Call snapshot() periodically (or on controlled shutdown) and use removeOldFiles() to prune obsolete logs after a successful snapshot.
+
+## Advanced Features
+
+### Indexing
+
+```kotlin
+// Define complex indexes
+val persistent = Persistent(
+  directory = File("data", "my-app"),
+  indexes = arrayOf(
+    index<Person>("ageOver30") { p -> ((p as? Person)?.age ?: 0) > 30 }
+  )
+)
+
+// Query using indexes
+persistent.query {
+  findByIndex<Person>("ageOver30", true).forEach { person ->
+    println("Person over 30: ${person.name}")
+  }
+}
+```
+
+### Transactions
+
+```kotlin
+// Read-only query
+persistent.query {
+  // Only read operations allowed
+}
+
+// Read-write transaction
+persistent.transaction {
+  // Both read and write operations allowed
+}
+```
+
+### Snapshots and Maintenance
+
+```kotlin
+// Create a snapshot of the current state
+persistent.snapshot()
+
+// Remove old transaction log files
+persistent.removeOldFiles()
+```
+
+## License
+
+This project is licensed under the MIT License - see the LICENSE file for details.