docs: add devMiddleware example

[snitin315]

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

No

Motivation / Use-Case

add devMiddleware option example.

Breaking Changes

None.

Additional Info

No

[codecov]

Codecov Report

Merging #3806 (41ce5bd) into master (e7c7009) will increase coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3806      +/-   ##
==========================================
+ Coverage   92.88%   93.03%   +0.15%     
==========================================
  Files          14       14              
  Lines        1321     1321              
  Branches      463      463              
==========================================
+ Hits         1227     1229       +2     
+ Misses         87       85       -2     
  Partials        7        7              

Impacted Files	Coverage Δ
lib/servers/WebsocketServer.js	97.14% <0.00%> (+5.71%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e7c7009...41ce5bd. Read the comment docs.