README: dedupe Try-it-live note from PR merge; add sparse-encoder tag for the SparseEncoder widget snippet

Integrate with Sentence Transformers (#2)

Model card: link the interactive HF Space demo (contributed by Apolinario / HF open-source team)

Make LICENSE reference a clickable link

Add Apache-2.0 LICENSE (matches github.com/naver/v-splade)

V-SPLADE initial release