fix: handle_gc_mod_list() return values in docs

[Green-Sky]

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This change is 

[JFreegman]

@JFreegman reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on Green-Sky).

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toxcore/group_chats.c line 3046 at r1 (raw file):

    if (unpack_ret == 1) {
        // validation failed
        return -2;

0 is likely the correct return code with incorrect/lacking documentation.

[JFreegman]

@JFreegman reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on Green-Sky).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.38%. Comparing base (093ff1a) to head (1d79022).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3062      +/-   ##
==========================================
- Coverage   69.84%   69.38%   -0.46%     
==========================================
  Files         185      185              
  Lines       34375    34422      +47     
==========================================
- Hits        24009    23884     -125     
- Misses      10366    10538     +172     

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