docs: add Pezkuwi-SDK documentation

- Technical documentation
- SDK guides
- Architecture overview
- Whitepaper
- Contributor guides

BACKPORT.md

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+# Backporting
+
+This document explains how to backport a merged PR from `master` to one of the `stable*` branches.
+Backports should only be used to fix bugs or security issues - never to introduce new features.
+
+## Steps
+
+1. Fix a bug through a PR that targets `master`.
+2. Add label related to the branch to wich to backport changes to the PR.
+    - `A4-backport-stable2409`
+    - `A4-backport-stable2412`
+    - `A4-backport-stable2503`
+    - `A4-backport-stable2506`
+3. Merge the PR into `master`.
+4. Wait for the bot to open the backport PR.
+5. Ensure the change is audited or does not need audit.
+6. Merge the backport PR.(ℹ️ for the branches starting from 2412 it can be done automatically
+    if backport PR has reviews and the pipeline is green)
+
+The label can also be added after the PR is merged.
+
+ℹ️ If, for some reasons, a backport PR was not created automatically, it can be done manually.
+But it is important, that the PR title follows the following pattern:
+`[stableBranchName] Backport #originalPRNumber` (i.e. **[stable2412] Backport #8198**)
+
+## Example
+
+For example here where the dev triggered the process by adding the label after merging:
+
+![backport](./images/backport-ex2.png)