Ragaaf - updated readme (#178)

* small fix for ragas.py

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* fixed error when metrics arg is used

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* updated README

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* added key features

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* edited formatting

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* improved readability

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* improved note in model section

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* spell check

Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>

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Signed-off-by: aasavari <aasavari.dhananjay.kakne@intel.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>