Fix link to genesis

[sabau]

• Closes Join Mainnet broken link #3890

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: sdkch add [section] [stanza] [message]

• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[cwgoes]

ACK, thanks

[codecov]

Codecov Report

Merging #3891 into develop will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3891      +/-   ##
===========================================
- Coverage    60.95%   60.94%   -0.02%     
===========================================
  Files          192      192              
  Lines        14360    14360              
===========================================
- Hits          8753     8751       -2     
- Misses        5033     5035       +2     
  Partials       574      574

[sabau]

Seems again broken:
https://cosmos.network/docs/gaia/join-mainnet.html#setting-up-a-new-node
https://raw.githubusercontent.com/cosmos/launch/master/latest/genesis.json