Docs: remove product hunt promo

[huynhicode]

📑 Summary

This PR contains updates to the Docs:

• remove announcement bar promoting Product Hunt debut
• update fourth card on the homepage to remove Product Hunt promo

Resolves # n/a

📏 Design Decisions

Design decisions made from within Mermaid Chart team.

📋 Tasks

Make sure you

• 📖 have read the contribution guidelines
• 💻 have added necessary unit/e2e tests.
• 📓 have added documentation. Make sure MERMAID_RELEASE_VERSION is used for all new features.
• 🔖 targeted develop branch

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[codecov]

Codecov Report

Merging #4938 (838ded4) into master (f1895ac) will decrease coverage by 3.43%.
Report is 195 commits behind head on master.
The diff coverage is 63.52%.

❗ Current head 838ded4 differs from pull request most recent head affe468. Consider uploading reports for the commit affe468 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4938      +/-   ##
==========================================
- Coverage   76.03%   72.61%   -3.43%     
==========================================
  Files         146      132      -14     
  Lines       14569    12077    -2492     
  Branches      592      592              
==========================================
- Hits        11078     8770    -2308     
+ Misses       3368     3165     -203     
- Partials      123      142      +19     

Flag	Coverage Δ
e2e	76.68% <74.43%> (-5.88%)	⬇️
unit	43.67% <24.45%> (-1.89%)	⬇️

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

Files	Coverage Δ
packages/mermaid/src/config.ts	67.61% <100.00%> (-6.89%)	⬇️
packages/mermaid/src/dagre-wrapper/index.js	98.82% <100.00%> (ø)
packages/mermaid/src/dagre-wrapper/markers.js	100.00% <100.00%> (ø)
...ages/mermaid/src/dagre-wrapper/mermaid-graphlib.js	90.95% <100.00%> (ø)
packages/mermaid/src/dagre-wrapper/nodes.js	66.00% <100.00%> (-23.63%)	⬇️
packages/mermaid/src/diagram-api/comments.ts	100.00% <100.00%> (+12.50%)	⬆️
...s/mermaid/src/diagram-api/diagram-orchestration.ts	83.33% <ø> (+43.79%)	⬆️
packages/mermaid/src/diagram-api/diagramAPI.ts	90.47% <100.00%> (+20.85%)	⬆️
packages/mermaid/src/diagrams/c4/c4Db.js	65.27% <ø> (+0.07%)	⬆️
packages/mermaid/src/diagrams/c4/c4Diagram.ts	100.00% <100.00%> (ø)
... and 31 more

... and 52 files with indirect coverage changes

[sidharthv96]

Closing in favour of existing #4903