Indicator logo is added. (#240)

# Describe Request

Indicator logo is added.

# Change Type

Documentation update.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Updated README to reflect enhancements in version 2 of the Indicator
Go module.
- Added a new logo and expanded introduction highlighting major
improvements.
- Introduced configurability for indicators and strategies without
preset values.
	- Detailed backtesting functionality with command line tool examples.
- Organized sections for indicators and strategies with clear headings
and documentation links.

- **Documentation**
	- Improved organization and clarity of the README content.
	- Updated licensing information for version 2 and above.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

README.md

@@ -1,5 +1,9 @@
 [![GoDoc](https://godoc.org/github.com/cinar/indicator/v2?status.svg)](https://godoc.org/github.com/cinar/indicator/v2) [![License](https://img.shields.io/badge/License-AGPLv3-blue.svg)](https://opensource.org/licenses/AGPLv3) [![Go Report Card](https://goreportcard.com/badge/github.com/cinar/indicator/v2)](https://goreportcard.com/report/github.com/cinar/indicator/v2) ![Go CI](https://github.com/cinar/indicator/actions/workflows/ci.yml/badge.svg) [![codecov](https://codecov.io/gh/cinar/indicator/graph/badge.svg?token=MB7L69UAWM)](https://codecov.io/gh/cinar/indicator)
 
+<p align="center">
+    <img src="logo.png" />
+</p>
+
 Indicator Go
 ============