Fix stale link

[yacovm]

Why this should be merged

The link to https://docs.avax.network/learn/virtual-machines is stale

How this works

Edited README.md

How this was tested

CI

How is this documented

[yacovm]

-test.shuffle 1729278387260396000
--- FAIL: TestTransactionSkipIndexing (32.58s)
    test_blockchain.go:[168](https://github.com/ava-labs/subnet-evm/actions/runs/11409487359/job/31749819661?pr=1368#step:7:169)8: 
        	Error Trace:	/Users/runner/work/subnet-evm/subnet-evm/core/test_blockchain.go:1688
        	            				/Users/runner/hostedtoolcache/go/1.22.8/arm64/src/runtime/asm_arm64.s:1222
        	Error:      	Not equal: 
        	            	expected: 0x5
        	            	actual  : 0x4
        	Test:       	TestTransactionSkipIndexing
        	Messages:   	expected tail to be 5, found 4
    test_blockchain.go:1685: 
        	Error Trace:	/Users/runner/work/subnet-evm/subnet-evm/core/test_blockchain.go:1685
        	            				/Users/runner/work/subnet-evm/subnet-evm/core/txindexer_test.go:231
        	            				/Users/runner/work/subnet-evm/subnet-evm/core/txindexer_test.go:253
        	            				/Users/runner/work/subnet-evm/subnet-evm/core/txindexer_test.go:227
        	Error:      	Condition never satisfied
        	Test:       	TestTransactionSkipIndexing
        	Messages:   	expected tail to be 5 eventually