Inline architecture diagram in README

[alexanderroidl]

This MR aims to inline the architecture diagram in the Mermaid format natively supported for inline-rendering by Markdown.

Preview

https://github.com/alexanderroidl/fredy/blob/4d5d7bf5c11cc5c765003762723aa50e9c3ffd9f/README.md

flowchart TD
 subgraph Jobs["Jobs"]
        A1["Job 1"]
        A2["Job 2"]
        A3["Job 3"]
  end
 subgraph Providers["Providers"]
        C1["Provider 1"]
        C2["Provider 2"]
        C3["Provider 3"]
  end
 subgraph NotificationAdapters["Notification Adapters"]
        F1["Notification Adapter 1"]
        F2["Notification Adapter 2"]
  end

    A1 --> B["FredyRuntime"]
    A2 --> B
    A3 --> B
    B --> C1 & C2 & C3
    C1 --> D["Similarity-Check"]
    C2 --> D
    C3 --> D
    D --> E{"Found<br>similarity?"}
    E -- No --> F1
    F1 --> F2

    style A1 fill:#fde9a0
    style A2 fill:#fde9a0
    style A3 fill:#fde9a0
    style C1 fill:#c4c9f1
    style C2 fill:#c4c9f1
    style C3 fill:#c4c9f1
    style F1 fill:#d2edba
    style F2 fill:#d2edba
    style B fill:#abd8f9
    style D fill:#fab4a8
    style E fill:#fffbb4

Loading

[orangecoding]

while I appreciate the effort, this chart is problematic in dark mode. see the font color.

[alexanderroidl]

Should be alright now:

[orangecoding]

There is 1 conflict. When resolved, we can merge it. Thanks!