feat:README.md: Section "Install ble-testsuite" is no longer valid

[Chetax]

Fixes Issue #30

📑 Description

Updated Execution command in section "Install ble-testsuite"

✅ Checks

• [X] My pull request adheres to the code style of this project
• [X] My code requires changes to the documentation
• [X] I have updated the documentation as required
• [X] All the tests have passed

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