Add blog post about FerretDB v0.8.1 release

[Fashander]

Description

Closes FerretDB/engineering#30

Readiness checklist

• I added unit tests for new functionality or bug fixes.
• I added integration tests for new functionality or bug fixes.
• I added compatibility tests for new functionality or bug fixes.
• I made spot refactorings.
• I updated user documentation.
• I ran task all, and it passed.
• I added/updated comments for both exported and unexported top-level declarations (functions, types, etc).
• I checked comments rendering with task godocs.
• I ensured that the title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Assignee, Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[codecov]

Codecov Report

Merging #1813 (2f3de60) into main (55180a0) will increase coverage by 7.97%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1813      +/-   ##
==========================================
+ Coverage   62.17%   70.15%   +7.97%     
==========================================
  Files         308      308              
  Lines       15176    15176              
==========================================
+ Hits         9435    10646    +1211     
+ Misses       4915     3561    -1354     
- Partials      826      969     +143     

Impacted Files	Coverage Δ
internal/wire/msg_header.go	69.04% <0.00%> (-2.39%)	⬇️
internal/handlers/common/filter.go	84.22% <0.00%> (ø)
integration/helpers.go	78.73% <0.00%> (+0.45%)	⬆️
internal/handlers/common/params.go	96.32% <0.00%> (+1.33%)	⬆️
internal/handlers/tigris/tjson/schema.go	81.52% <0.00%> (+1.63%)	⬆️
internal/handlers/pg/pgdb/database_metadata.go	85.54% <0.00%> (+3.61%)	⬆️
internal/handlers/tigris/tjson/document.go	46.98% <0.00%> (+3.61%)	⬆️
integration/setup/setup.go	79.06% <0.00%> (+4.65%)	⬆️
internal/handlers/pg/pgdb/collections.go	69.29% <0.00%> (+4.72%)	⬆️
internal/handlers/tigris/tigrisdb/collections.go	66.66% <0.00%> (+4.76%)	⬆️
... and 41 more

Flag	Coverage Δ
integration	66.47% <ø> (+11.17%)	⬆️
mongodb	14.64% <ø> (+0.01%)	⬆️
pg	55.19% <ø> (-0.03%)	⬇️
tigris	45.75% <ø> (?)
unit	28.40% <ø> (+0.20%)	⬆️

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

[rumyantseva]

I like how we highlighted the features in this post!

I added a couple of suggestions to make the code part a bit more consistent/readable.

[chilagrow]

Tiny comment

[rumyantseva]

Distinct command explanation needs to be updated (as the current one is for runCommand, the rest looks good to me!

[rumyantseva]

LGTM