Update developer-guide.md

[computerscienceiscool]

Fixed a couple of spelling errors

We are excited to review your PR.

So we can do the best job, please check:

• There's a descriptive title that will make sense to other developers some time from now.
• There's associated issues. All PR's should have issue(s) associated - unless a trivial self-evident change such as fixing a typo. You can use the format Fixes #nnnn in your description to cause GitHub to automatically close the issue(s) when your PR is merged.
• Your change description explains what the change does, why you chose your approach, and anything else that reviewers should know.
• You have included any necessary tests in the same PR.

[codecov]

Codecov Report

Merging #6870 (38a729c) into main (766569b) will increase coverage by 0.01%.
Report is 2 commits behind head on main.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##             main    #6870      +/-   ##
==========================================
+ Coverage   69.40%   69.41%   +0.01%     
==========================================
  Files        1238     1238              
  Lines      249441   249441              
  Branches    25522    25520       -2     
==========================================
+ Hits       173130   173155      +25     
+ Misses      69692    69539     -153     
- Partials     6619     6747     +128     

Flag	Coverage Δ
Debug	69.41% <60.00%> (+0.01%)	⬆️
production	63.94% <60.00%> (+0.01%)	⬆️
test	88.90% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
.../Microsoft.Data.Analysis/VBufferDataFrameColumn.cs	45.77% <60.00%> (-1.41%)	⬇️

... and 15 files with indirect coverage changes

[michaelgsharp]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[michaelgsharp]

Thanks for the fixes!

[michaelgsharp]

Merging since its just a doc fix.