docs: improve README clarity and add Windows notes

[AswaniSahoo]

Description

This PR improves the README documentation with minor typo fixes and adds Windows-specific guidance for developers.

Changes made:

• Fixed grammatical error: virtual environments → virtual environment's (line 23)
• Removed duplicate word: in the from EUMETSAT → from EUMETSAT (line 111)
• Added Windows compatibility note explaining that make commands require GNU Make
• Clarified the relationship between uv and make in the development notes

Motivation:
As a Windows user setting up this project, I found that the make commands failed without explanation. These documentation improvements will help future Windows contributors get started more easily and reduce setup friction.

Fixes # (No issue - documentation improvement)

How Has This Been Tested?

• Yes

Testing performed:

• Verified README renders correctly in VS Code markdown preview
• Checked that all markdown formatting is correct (alerts, code blocks, tables)
• Confirmed no broken links or formatting issues introduced
• Validated that the Windows note appears in the correct location

N/A - This PR only modifies documentation, no data processing changes.

• Yes

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works (N/A - documentation only)
• I have checked my code and corrected any misspellings

[Copilot]

Pull request overview

This PR improves the README documentation by fixing grammatical errors and adding Windows-specific guidance to help developers on Windows understand how to work with the project's build commands.

Key changes:

• Fixed two grammatical errors in the documentation (possessive form and duplicate phrase removal)
• Added a Windows compatibility note explaining GNU Make requirement
• Clarified that both uv and GNU Make are needed for the convenience make commands

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