Specify kotlinx lib requirements in README.md (#870)

## Motivation and Context
Unfortunately, Kotlin lib requirements are not explicitly stated in
README and users encounter errors in runtime in existing projects with
Spring, for example, here: #273
and #678 And they might
encounter serialization errors while trying the Persistency feature.

## Breaking Changes
None

---

#### Type of the changes
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update
- [ ] Tests improvement
- [ ] Refactoring

#### Checklist
- [x] The pull request has a description of the proposed change
- [ ] I read the [Contributing
Guidelines](https://github.com/JetBrains/koog/blob/main/CONTRIBUTING.md)
before opening the pull request
- [x] The pull request uses **`develop`** as the base branch
- [ ] Tests for the changes have been added
- [ ] All new and existing tests passed

##### Additional steps for pull requests adding a new feature
- [ ] An issue describing the proposed change exists
- [ ] The pull request includes a link to the issue
- [ ] The change was discussed and approved in the issue
- [ ] Docs have been added / updated

Author: serge-p7v

README.md

@@ -76,17 +76,18 @@ fun main() = runBlocking {
 
 Currently, the framework supports the JVM, JS, WasmJS and iOS targets.
 
-On JVM, JDK 17 or higher is required to use the framework.
+### Requirements
 
-Please check the [libs.versions.toml](gradle/libs.versions.toml) to know more about the Koog dependencies.
+- JDK 17 or higher is required to use the framework on JVM.
+- kotlinx-coroutines 1.10.2 and kotlinx-serialization 1.8.1 versions should be set explicitly in existing projects. Please check the [libs.versions.toml](gradle/libs.versions.toml) to know more about the Koog dependencies.
 
 ### Gradle (Kotlin DSL)
 
 1. Add dependencies to the `build.gradle.kts` file:
 
     ```
     dependencies {
-        implementation("ai.koog:koog-agents:0.4.1")
+        implementation("ai.koog:koog-agents:0.4.2")
     }
     ```
 2. Make sure that you have `mavenCentral()` in the list of repositories.
@@ -96,7 +97,7 @@ Please check the [libs.versions.toml](gradle/libs.versions.toml) to know more ab
 
     ```
     dependencies {
-        implementation 'ai.koog:koog-agents:0.4.1'
+        implementation 'ai.koog:koog-agents:0.4.2'
     }
     ```
 2. Make sure that you have `mavenCentral()` in the list of repositories.
@@ -108,7 +109,7 @@ Please check the [libs.versions.toml](gradle/libs.versions.toml) to know more ab
     <dependency>
         <groupId>ai.koog</groupId>
         <artifactId>koog-agents-jvm</artifactId>
-        <version>0.4.1</version>
+        <version>0.4.2</version>
     </dependency>
     ```
 2. Make sure that you have `mavenCentral` in the list of repositories.