feat: Added documentation for OHIF-v3 (#2450)

* Added docs with new screenshots

* Added doc to architecture

* Added documentations to various extension modules

* Added more documentation to modes

* Added docs to managers

* Added docs for services

* Fixed deployment docs

* Added white labelling documentation

* Added i18n docs and measurement export

docs/latest/managers/extension.md

@@ -0,0 +1,50 @@
+# Extension Manager
+
+## Overview
+The `ExtensionManager` is a class made available to us via the `@ohif/core`
+project (platform/core). Our application instantiates a single instance of it,
+and provides a `ServicesManager` and `CommandsManager` along with the
+application's configuration through the appConfig key (optional).
+
+```js
+const commandsManager = new CommandsManager();
+const servicesManager = new ServicesManager();
+const extensionManager = new ExtensionManager({
+  commandsManager,
+  servicesManager,
+  appConfig,
+});
+```
+
+The `ExtensionManager` only has a few public members:
+
+- `setActiveDataSource` - Sets the active data source for the application
+- `getDataSources` - Returns the registered data sources
+- `getActiveDataSource` - Returns the currently active data source
+- `getModuleEntry` - Returns the module entry by the give id.
+
+
+## Accessing Modules
+
+We use `getModuleEntry` in our `ViewerLayout` logic to find the panels based on the
+provided IDs in the mode's configuration.
+
+
+For instance: `extensionManager.getModuleEntry("org.ohif.measurement-tracking.panelModule.seriesList")`
+accesses the `seriesList` panel from `panelModule` of the `org.ohif.measurement-tracking` extension.
+
+
+```js
+const getPanelData = id => {
+  const entry = extensionManager.getModuleEntry(id);
+  const content = entry.component;
+
+  return {
+    iconName: entry.iconName,
+    iconLabel: entry.iconLabel,
+    label: entry.label,
+    name: entry.name,
+    content,
+  };
+};
+```