docs: regenerate governance diagrams (#3927)

* docs: regenerate governance diagrams

Following #3888, add a shell script to generate the diagrams.
Rename the files for better consistency.
Check in new .pngs, since the .pumls were recently updated.

* chore: add a final newline

packages/governance/docs/contractGovernance.puml

@@ -1,4 +1,4 @@
-@startuml contract governance
+@startuml contractGovernance
 
 package "GovernedContract Vat" <<Rectangle>>  {
     Object ParamManager {

packages/governance/docs/coreArchitecture.puml

@@ -1,4 +1,4 @@
-@startuml governance invitation linkages
+@startuml coreArchitecture
 
 package Legend <<Rectangle>> #EEEEEE {
 

packages/governance/docs/example.puml

@@ -1,4 +1,4 @@
-@startuml governance example
+@startuml governanceExample
 
 package "Example with Vote Invitation" <<rectangle>> {
   class ContractGovernor {

packages/governance/docs/gen.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+pumljar="${PLANTUML:-$HOME/plantuml/plantuml.jar}"
+page="index.md"
+java -jar "$pumljar" "./**/*.puml"
+echo "# Governance Diagrams" > "$page"
+for diag in $(find . -name "*.png" | sort); do
+    echo "## $diag\n" >> "$page"
+    echo "[![$diag]($diag)]($diag)\n" >> "$page"
+done

packages/governance/docs/index.md

@@ -0,0 +1,13 @@
+# Governance Diagrams
+## ./contractGovernance.png
+
+[![./contractGovernance.png](./contractGovernance.png)](./contractGovernance.png)
+
+## ./coreArchitecture.png
+
+[![./coreArchitecture.png](./coreArchitecture.png)](./coreArchitecture.png)
+
+## ./governanceExample.png
+
+[![./governanceExample.png](./governanceExample.png)](./governanceExample.png)
+