feat: adds warning to main README + removed other warnings

[simzzz]

Description:
This PR adds a warning to the end users that all contracts are experimental and have not been audited.

Related issue(s):

Fixes #1217

Notes for reviewer:

Checklist

[github-actions]

Test Results

 16 files   -  1   99 suites   - 4   24m 6s ⏱️ + 7m 42s
355 tests +18  335 ✅ +22  19 💤 +6  1 ❌  - 10 
451 runs   - 16  429 ✅  - 13  21 💤 +7  1 ❌  - 10 

For more details on these failures, see this check.

Results for commit 6eeea49. ± Comparison against base commit 3aa1542.

This pull request removes 21 and adds 39 tests. Note that renamed tests count towards both.

"before all" hook for "should cancel a pending airdrop for a fungible token (FT)" ‑ HIP904 IHRC904Facade ContractTest Suite "before all" hook for "should cancel a pending airdrop for a fungible token (FT)"
"before all" hook for "should cancel a single pending fungible token airdrop" ‑ HIP904 CancelAirdropContract Test Suite "before all" hook for "should cancel a single pending fungible token airdrop"
"before all" hook for "should claim a single pending fungible token airdrop" ‑ HIP904 ClaimAirdropContract Test Suite "before all" hook for "should claim a single pending fungible token airdrop"
"before all" hook for "should reject tokens for a single account" ‑ HIP904 TokenRejectContract Test Suite "before all" hook for "should reject tokens for a single account"
"before each" hook for "Should check if an address is another address's operator" ‑ @OZERC1155Token Test Suite "before each" hook for "Should check if an address is another address's operator"
should NOT be able to use transferFrom on NFT tokens without approval ‑ TokenTransferContract Test Suite should NOT be able to use transferFrom on NFT tokens without approval
should NOT be able to use transferFrom on fungible tokens without approval ‑ TokenTransferContract Test Suite should NOT be able to use transferFrom on fungible tokens without approval
should be able to execute cryptoTransfer for hbar transfer only ‑ TokenTransferContract Test Suite should be able to execute cryptoTransfer for hbar transfer only
should be able to execute cryptoTransfer for nft only ‑ TokenTransferContract Test Suite should be able to execute cryptoTransfer for nft only
should be able to execute cryptoTransfer with both 3 txs ‑ TokenTransferContract Test Suite should be able to execute cryptoTransfer with both 3 txs
…

"before all" hook in "HIP583 Test Suite - Ethereum Transfer TX via system-contracts" ‑ HIP583 Test Suite - Ethereum Transfer TX via system-contracts "before all" hook in "HIP583 Test Suite - Ethereum Transfer TX via system-contracts"
Should NOT allow a non-operator to transfer tokens to another account ‑ @OZERC1155Token Test Suite Should NOT allow a non-operator to transfer tokens to another account
Should NOT burn insufficient amount of token ‑ @OZERC1155Token Test Suite Should NOT burn insufficient amount of token
Should NOT transfer the ownership to another account if the caller is not owner ‑ @OZERC1155Token Test Suite Should NOT transfer the ownership to another account if the caller is not owner
Should allow an operator to transfer a token to another account ‑ @OZERC1155Token Test Suite Should allow an operator to transfer a token to another account
Should allow an operator to transfer tokens in batch to another account ‑ @OZERC1155Token Test Suite Should allow an operator to transfer tokens in batch to another account
Should burn token in batch ‑ @OZERC1155Token Test Suite Should burn token in batch
Should burn token ‑ @OZERC1155Token Test Suite Should burn token
Should check if an address is another address's operator ‑ @OZERC1155Token Test Suite Should check if an address is another address's operator
Should retrieve the token uri of a tokenID ‑ @OZERC1155Token Test Suite Should retrieve the token uri of a tokenID
…