Use mermaid for "defmt ecosystem" diagram

CHANGELOG.md

@@ -9,9 +9,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - [#766] `decoder::log`: Rename `PrettyLogger` to `StdoutLogger`
 - [#765]: `defmt-decoder`: Add support for customizable logger formatting
+- [#764]: Use mermaid for "defmt ecosystem" diagram
 
 [#766]: https://github.com/knurling-rs/defmt/pull/766
 [#765]: https://github.com/knurling-rs/defmt/pull/765
+[#764]: https://github.com/knurling-rs/defmt/pull/764
 
 ## [v0.3.5] - 2023-06-19
 

README.md

@@ -29,7 +29,40 @@ It still might work on older rust versions, but this isn't ensured.
 
 The following diagram illustrates the user-facing and internal crates of the defmt framework.
 
-![defmt crates structure](assets/defmt.png)
+```mermaid
+%%{ init: { 'flowchart': { 'curve': 'step', "defaultRenderer": "elk" } } }%%
+graph TD;
+    A[[defmt]]
+    B[defmt-decoder]
+    C[defmt-itm]
+    D[defmt-macros]
+    E[defmt-parser]
+    F[defmt-print]
+    G[defmt-rtt]
+    H(defmt-semihosting)
+    I[[defmt-test]]
+    J[defmt-test-macros]
+    K[[flip-link]]
+    L[panic-probe]
+    M[[probe-run]]
+    N(qemu-run)
+
+    A --> D
+    B & D --o E
+    C & G & H & I & L --> A
+    F & M & N --o B
+    I --o J
+
+    subgraph Legend
+    O[[user facing crate]]
+    P[internal crate]
+    Q(unreleased crate)
+    O -- dependency --> P
+    Q -- pinned dependency --o P
+    end
+
+    J ~~~ Legend
+```
 
 ## Developer Information