docs: improve token ID placeholders and add wallet funding note

[contbytex]

Description

This PR improves the developer experience in the CLI documentation by addressing a few minor points:

1. Token ID Clarity: Replaced hardcoded specific token IDs (e.g., 48331043336612883...) with the generic <TOKEN_ID> placeholder across the examples. This prevents confusion for users who might try to copy/paste the commands directly.
2. Wallet Funding Context: Added a brief note in the "Contract Approvals" section clarifying how users can view their generated wallet address (polymarket wallet show) and fund it with MATIC and USDC.e on Polygon before attempting to run polymarket approve set.

These minor changes should help reduce friction for users setting up the CLI for the first time.

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Note

Low Risk
Low risk documentation-only changes; no runtime behavior or API contracts are modified.

Overview
Updates README.md examples to use generic placeholders (e.g., <TOKEN_ID>, 0xCONDITION_ID, 0xCOLLECTION_ID) instead of copy-pastable real-looking IDs, and adds a note in Contract Approvals about funding the generated wallet (view via polymarket wallet show, fund with MATIC/USDC.e on Polygon) before running polymarket approve set.

Also tweaks markdown formatting for code blocks (use text fences) and simplifies sample JSON output so it doesn’t imply omitted fields.

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