docs: add about content cutomization doc file

doc/README.md

@@ -8,3 +8,4 @@
 - [Scenario Parameters configuration](scenarioParametersConfiguration.md)
 - [Scenario Parameters advanced customization](scenarioParametersCustomization.md)
 - [Theme Customization](themeCustomization.md)
+- [About Content Customization](aboutContentCustomization.md)

doc/aboutContentCustomization.md

@@ -0,0 +1,64 @@
+# About customization
+
+## Customization of About content component
+
+By default, About content customization is set in the React component:
+[src/components/AboutContent/AboutContent.js](../src/components/AboutContent/AboutContent.js)
+
+## About content configuration
+
+- In the same [AboutContent.js](../src/components/AboutContent/AboutContent.js) file,
+  **title** and **text** contents are set through these translation keys:
+
+  ```jsx
+    <Grid className={classes.title} item>
+      {t('genericcomponent.dialog.about.title')}
+    </Grid>
+    ...
+    <Grid item className={classes.content}>
+      {t('genericcomponent.dialog.about.content')}
+    </Grid>
+  ```
+
+  and translation files:
+
+  [public/locales/en/translation.json](../public/locales/en/translation.json)
+
+  [public/locales/fr/translation.json](../public/locales/fr/translation.json)
+
+- Webapp **version number** is automaticaly fetched from [package.json](package.json) at deployment.
+  So, don't forget to keep up-to-date the variable `version`:
+
+  ```json
+  {
+    "name": "azure-sample-webapp",
+    "version": "2.1.0",
+    "private": true,
+    "dependencies": {
+  ```
+
+## Enable or disable About entry in help menu
+
+In file [src/services/config/Menu.js](../src/services/config/Menu.js):
+
+- To **enable** About entry in help menu.
+  `About` constant must be set with **About content component**.
+
+  By default, the constant is set like that:
+
+  ```js
+  import { AboutContent } from '../../components/AboutContent';
+
+  export const About = AboutContent;
+  ```
+
+  If you want to use another component, don't forget to set correctly the `import` line.
+
+- To **disable** About entry in help menu.
+  `About` constant must be set as **_null_** :
+
+  ```js
+  // import { AboutContent } from '../../components/AboutContent';
+
+  export const About = null;
+  ```