Add introductory colons to points in Overview

[parthagar]

Points under Acceleration, Security and Authorization, AI Integrations and Tools and Ecosystem sections were difficult to read because of missing delimiters between topic of that point and the description.

[sre-ci-robot]

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[sre-ci-robot]

Welcome @parthagar! It looks like this is your first PR to milvus-io/milvus-docs 🎉

[parthagar]

@AnthonyTsu1984 can you check this PR and guide me on the next steps, should I create an issue for this?