fix: readme: Update install instructions link

[blademasterzhang]

find the link is fault, modify https://docs.filecoin.io/get-started/lotus to https://lotus.filecoin.io

Related Issues

Proposed Changes

Additional Info

Checklist

Before you mark the PR ready for review, please make sure that:

• All commits have a clear commit message.
• The PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
  • PR type: fix, feat, INTERFACE BREAKING CHANGE, CONSENSUS BREAKING, build, chore, ci, docs,perf, refactor, revert, style, test
  • area: api, chain, state, vm, data transfer, market, mempool, message, block production, multisig, networking, paychan, proving, sealing, wallet, deps
• This PR has tests for new functionality or change in behaviour
• If new user-facing features are introduced, clear usage guidelines and / or documentation updates should be included in https://lotus.filecoin.io or Discussion Tutorials.
• CI is green

[codecov]

Codecov Report

Merging #8460 (73203f6) into master (e2f4c70) will decrease coverage by 0.05%.
The diff coverage is n/a.

❗ Current head 73203f6 differs from pull request most recent head f0c12a0. Consider uploading reports for the commit f0c12a0 to get more accurate results

@@            Coverage Diff             @@
##           master    #8460      +/-   ##
==========================================
- Coverage   40.68%   40.62%   -0.06%     
==========================================
  Files         686      686              
  Lines       75441    75441              
==========================================
- Hits        30691    30649      -42     
- Misses      39448    39484      +36     
- Partials     5302     5308       +6     

Impacted Files	Coverage Δ
chain/events/message_cache.go	87.50% <0.00%> (-12.50%)	⬇️
chain/actors/builtin/miner/diff.go	48.52% <0.00%> (-10.30%)	⬇️
storage/wdpost_sched.go	75.49% <0.00%> (-5.89%)	⬇️
chain/exchange/client.go	49.15% <0.00%> (-5.51%)	⬇️
chain/stmgr/call.go	69.18% <0.00%> (-3.25%)	⬇️
blockstore/autobatch.go	56.30% <0.00%> (-1.69%)	⬇️
lib/rpcenc/reader.go	70.29% <0.00%> (-1.49%)	⬇️
chain/events/events_called.go	86.34% <0.00%> (-0.98%)	⬇️
extern/sector-storage/sched.go	84.77% <0.00%> (-0.83%)	⬇️
chain/sync.go	70.52% <0.00%> (-0.69%)	⬇️
... and 11 more

[jennijuju]

Thank you for the PR - suggested to change to the section that can lead user directly to the installation instructions