docs(maintainers): add cicd pipeline diagram

MAINTAINERS.md

@@ -198,7 +198,7 @@ Once complete, you can start drafting the release notes to let customers know **
 
 Every release makes hundreds of checks, security scans, canaries and deployments - all of these are automated.
 
-This is a close visual representation of the main steps (GitHub Actions UI should be the source of truth).
+This is a close visual representation of the main steps (GitHub Actions UI should be the source of truth), along with the approximate time it takes for each key step to complete.
 
 <!-- use 8s to graph steps faster than 8s like seal/checksum that actually takes 0s -->
 
@@ -258,6 +258,106 @@ section Post-release
 Release complete : milestone, m6, 10:31,2m
 ```
 
+If we combine our CI and CD pipelines into a single diagram, it looks like this:
+
+```mermaid
+timeline
+    title Powertools for AWS Lambda (Python) CI/CD pipeline
+
+    section Continuous Integration
+    Project setup <br> (make dev)   : Code checkout
+                                    : Virtual environment
+                                    : Dependencies
+                                    : Git pre-commit hooks
+                                    : Local branch
+                                    : Local changes
+                                    : Local tests
+
+    Pre-commit checks <br> (git commit)     : Merge conflict check
+                                            : Trailing whitespaces
+                                            : TOML checks
+                                            : Code linting (standards)
+                                            : Markdown linting
+                                            : CloudFormation linting
+                                            : GitHub Actions linting
+                                            : Terraform linting
+                                            : Secrets linting
+
+    Pre-Pull Request <br> (make pr)     : Code linting
+                                        : Docs linting
+                                        : Static typing analysis
+                                        : Tests (unit|functional|perf)
+                                        : Security baseline
+                                        : Complexity baseline
+                                        : +pre-commit checks
+
+    Pull Request <br> (CI checks)   : Semantic PR title check
+                                    : Related issue check
+                                    : Acknowledgment check
+                                    : Code coverage diff
+                                    : Contribution size check
+                                    : Contribution category check
+                                    : Dependency vulnerability check
+                                    : GitHub Actions security check
+                                    : +pre-pull request checks
+
+    After merge <br> (CI checks)    : End-to-end tests
+                                    : Longer SAST check
+                                    : Security posture check (scorecard)
+                                    : GitHub Actions security check
+                                    : Rebuild Changelog
+                                    : Deploy staging docs
+                                    : Update draft release
+
+    section Continuous Delivery
+
+    Source code anti-tampering  : Checkout release commit code
+                                : Bump release version
+                                : Seal and upload artifact
+
+    Quality Assurance           : Restore sealed code
+                                : +Continuous Integration checks
+
+    Build                       : Restore sealed code
+                                : Integrity check
+                                : Build release artifact
+                                : Seal and upload artifact
+
+    Release                     : Restore sealed build
+                                : Integrity check
+                                : PyPi ephemeral credentials
+                                : Publish PyPi
+                                : Baking time
+
+    Git tagging                 : Restore sealed code
+                                : Integrity check
+                                : Bump git tag
+                                : Create temporary branch
+                                : Create PR
+
+    Lambda Layers               : Fetch PyPi release
+                                : Build x86 architecture
+                                : Build ARM architecture
+                                : Deploy Beta
+                                : Canary testing
+                                : Deploy Prod
+
+    Lambda Layers SAR           : Deploy Beta
+                                : Deploy Prod
+
+    Documentation               : Update Lambda Layer ARNs
+                                : Build User Guide
+                                : Build API Guide
+                                : Rebuild Changelog
+                                : Release new version
+                                : Update latest alias
+                                : Create temporary branch
+                                : Create PR
+
+    Post-release                : Close pending-release issues
+                                : Notify customers
+```
+
 #### Drafting release notes
 
 Visit the [Releases page](https://github.com/aws-powertools/powertools-lambda-python/releases) and choose the edit pencil button.