add possibility to run some workflows manually

.github/workflows/codeql-analysis.yml

@@ -1,6 +1,7 @@
 name: "CodeQL"
 
 on:
+  workflow_dispatch:
   push:
     branches: [ main ]
   pull_request:

.github/workflows/generate-readme.yml

@@ -1,5 +1,6 @@
 name: Generate README
 on:
+  workflow_dispatch:
   push:
     branches:
       - main

.github/workflows/prettify-json.yml

@@ -1,5 +1,6 @@
 name: Prettify people.json
 on:
+  workflow_dispatch:
   push:
     paths:
       - 'people.json'

.github/workflows/validate-markdown.yml

@@ -1,5 +1,6 @@
 name: Markdown Syntax Validation
 on:
+  workflow_dispatch:
   push:
     paths:
       - 'scripts/README-TEMPLATE.md'