Improve README.md for better project discoverability

[Copilot]

Enhanced the README.md file to improve onboarding experience for new users and contributors by adding missing essential sections about installation and quick start with a usage example.

Fixes #63.

[Copilot]

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[llucax]

• If you add an installation guide use python3 -m pip ... instead of just pip ... if you are adding pip commands. Also explain how to add the dependency in pyproject.toml. Like (adapt as needed with the correct library name and use the latest github release to take the version number of the library when pinning/as the minimum dependency):

  ```toml
  [project]
  dependencies = [
      "<the-lib> >= 1.0.0, < 2",
  ]
  ```
  > [!NOTE]
  > We recommend pinning the dependency to the latest version for programs,
  > like `"<the-lib> == 1.0.1"`, and specifying a version range spanning
  > one major version for libraries, like `"<the-lib> >= 1.0.1, < 2"`.
  > We follow [[semver](https://semver.org/)](<https://semver.org/>).

Make sure the structure/order of sections of the README should generally be:

• Introduction
• Supported Platforms
• Installation
• Quick Start
• Documentation (saying only something like “For complete API documentation, examples, and advanced usage patterns, see ”).
• Contributing

The amount and name of sections don’t have to match 100%, if there are already existing similar sections, leave them, but try to match the order above.

Please also check that the Supported Platforms section is up to date by checking which Python versions, operating systems (typically Ubuntu versions) and architectures are currently being tested by the CI GitHub workflow and update it if they are not up to date.

@copilot

[Copilot]

• If you add an installation guide use python3 -m pip ... instead of just pip ... if you are adding pip commands. Also explain how to add the dependency in pyproject.toml. Like (adapt as needed ...

I've updated the installation section to include proper version pinning guidance. The changes include:

• Added a NOTE section explaining the difference between version pinning for programs (== 1.0.0) vs libraries (>= 1.0.0, < 2)
• Used the latest release version (1.0.0) from the GitHub releases
• Added reference to semantic versioning
• Already using python3 -m pip command format as requested

The installation guide now provides clear guidance for both use cases while following semver best practices.

[Copilot]

Pull Request Overview

This PR enhances the README.md file to improve project discoverability and onboarding by adding essential documentation sections. The changes provide clear guidance for new users on how to get started with the frequenz-quantities library.

• Added installation instructions for both pip and pyproject.toml dependency management
• Included a Quick Start section with practical code examples demonstrating basic usage
• Added versioning recommendations following semantic versioning best practices

Comments suppressed due to low confidence (1)

README.md:1

• The example version >= 1.0.0, < 2 should be updated to reflect actual available versions of the package to avoid confusion for users.

# Frequenz Quantities Library

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