doc: add description for generation of priv_validator_key to config.toml

[jaeseung-bae]

Description

• Add descriptive comment for the config value(priv_validator_laddr)

[codecov]

Codecov Report

Merging #705 (cec07b1) into main (449aa31) will increase coverage by 0.10%.
Report is 4 commits behind head on main.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #705      +/-   ##
==========================================
+ Coverage   66.54%   66.64%   +0.10%     
==========================================
  Files         285      285              
  Lines       37915    37915              
==========================================
+ Hits        25229    25270      +41     
+ Misses      10878    10845      -33     
+ Partials     1808     1800       -8     

Files Changed	Coverage Δ
config/toml.go	74.19% <ø> (ø)

... and 15 files with indirect coverage changes