Fixing GenerateIndex for Multiple RCs

[nicholasSUSE]

• Issue: Adjust index generation to support multiple RCs #100
• Use this instead of: (fix?) do not create a copy of helm index using index.Merge() #190

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make charts was not able to create multiple RC's because of a bug at helm package when detecting different versions like:

100.0.0-rc.1
100.0.0

These should have been detected as different versions, but they were not detected.

I provided a workaround that will use the newest index.yaml generated from the assets folder.
Instead of merging it into the old index.yaml opened from the static file.
It will just use the newly generated one and compare it to the old one.