Fix readme and qm7.json

[HuangJiameng]

• correct the wrong spelling of "perturb" and "perturbation" in README.md
• remove "load_ckpt", see load_ckpt should be removed from README.md #813

[codecov-commenter]

Codecov Report

Merging #817 (265093c) into devel (8750a83) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            devel     #817   +/-   ##
=======================================
  Coverage   35.13%   35.13%           
=======================================
  Files          96       96           
  Lines       16808    16808           
=======================================
  Hits         5905     5905           
  Misses      10903    10903           

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[njzjz]

Can you also remove load_ckpt from other examples?

[HuangJiameng]

Can you also remove load_ckpt from other examples?

I have updated 2 examples without specific dp version.