[docs] add metadata + overview + update draft (#13732)

[frapuks]

DO NOT MERGE BEFORE REMOVING DRAFT_WORKFLOW FEATURE FLAG

Proposed changes

• update doc about :
  • metadata
  • overview
  • update draft
  • bottom bar

• Update screenshots

Related issues

• [doc] Authorize Members on draft + new tab in Restricted #13732
• Workflow: Ability to Add Metadata to Draft #14058

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant uses case (coverage and e2e)
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 32.62%. Comparing base (56915dd) to head (08803c2).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #15317   +/-   ##
=======================================
  Coverage   32.62%   32.62%           
=======================================
  Files        3148     3148           
  Lines      213790   213792    +2     
  Branches    38776    38777    +1     
=======================================
+ Hits        69749    69752    +3     
+ Misses     144041   144040    -1     

Flag	Coverage Δ
opencti-client-python	45.52% <ø> (ø)
opencti-front	2.86% <ø> (-0.01%)	⬇️
opencti-graphql	67.85% <ø> (+<0.01%)	⬆️

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