doc(readme): format docs.

[halibobo1205]

What does this PR do?
format docs.
Why are these changes required?

This PR has been tested by:

• Unit Tests
• Manual Testing

Follow up

Extra details

[codecov-commenter]

Codecov Report

Merging #4535 (5bcb4e1) into develop (80f04d8) will increase coverage by 0.01%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             develop    #4535      +/-   ##
=============================================
+ Coverage      54.25%   54.26%   +0.01%     
- Complexity      7889     7891       +2     
=============================================
  Files            826      826              
  Lines          46785    46785              
  Branches        5075     5075              
=============================================
+ Hits           25383    25388       +5     
  Misses         19369    19369              
+ Partials        2033     2028       -5     

Impacted Files	Coverage Δ
...org/tron/core/exception/ItemNotFoundException.java	33.33% <0.00%> (-33.34%)	⬇️
...rc/main/java/org/tron/core/db/BlockIndexStore.java	50.00% <0.00%> (-8.34%)	⬇️
.../src/main/java/org/tron/core/ChainBaseManager.java	90.90% <0.00%> (-1.40%)	⬇️
...mework/src/main/java/org/tron/core/db/Manager.java	53.68% <0.00%> (+0.33%)	⬆️
...ain/java/org/tron/core/db/backup/BackupDbUtil.java	85.10% <0.00%> (+2.12%)	⬆️
...ain/java/org/tron/consensus/dpos/StateManager.java	56.25% <0.00%> (+4.16%)	⬆️
...mon/overlay/discover/table/DistanceComparator.java	100.00% <0.00%> (+20.00%)	⬆️

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