Fix MetricGardenerImporter Documentation

[ce-bo]

The MetricGardenerImporter Readme is not up to date.
Please adjust it to match the current parser.

Acceptance Criteria

• There is a short introduction text to inform the user about that it can be used to parse files locally or to just import a given metric-gardener json file.
• The info is fixed, so that it is not optional to compress files. Indeed it is the default behavior.
• There is a link to the Documentation (GitHub Page) with a short hint that the user can find more information and usage examples there.
• On the GitHub Page in the "Manual Mode" section, please note that metric-gardener command has to be installed before running npx metric-gardener parse /path/to/source/code -o mg_results.json by for example running npm i -g metric-gardener
• Automatic mode (ccsh runs MetricGardener internally): is renamed to Create a CodeCharta json file from local source code (metric-gardener is executed internally on the fly):
• Manual mode (run MetricGardener yourself): is renamed to Create a CodeCharta json file by importing a given metric-gardener json file (run MetricGardener yourself):