fix: subspaces CLI commands and Proto files wrong notations

[leobragaz]

This PR aim to solve some minor issues that I've found inside the x/subspaces module.

1. Updates the groups CLI commands examples
2. Fixes wrong notations in subspaces models proto file
3. Add missing GetCmdDeleteSubspace to the TxCmd
4. Add missing GetCmdQueryUserGroup to the QueryCmd

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[RiccardoM]

We need a changeset entry here

[codecov]

Codecov Report

Merging #815 (164f6c8) into master (5475bfe) will not change coverage.
The diff coverage is n/a.

❗ Current head 164f6c8 differs from pull request most recent head 8732802. Consider uploading reports for the commit 8732802 to get more accurate results

@@           Coverage Diff           @@
##           master     #815   +/-   ##
=======================================
  Coverage   81.33%   81.33%           
=======================================
  Files          81       81           
  Lines        6843     6843           
=======================================
  Hits         5566     5566           
  Misses       1017     1017           
  Partials      260      260           

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[leobragaz]

I found that GetCmdQueryUserGroup() was missing and added it