doc(server): add basic architecture overview of resource manager (#2401)

server/resourcemanager/README.md

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+# Resource Manager
+
+`ResourceManager` provides reusable shared operations among resources. This includes the CRUD operations via HTTP, support for different output encodings (yaml or JSON), and Provisioning.
+
+
+## What is a Resource?
+
+A `Resource` is, conceptually, any entity that can be created, read, updated and/or deleted.
+Some examples in Tracetest includes `Test`, `Transaction`, `PollingProfile`, etc.
+
+## How this works
+
+A `ResourceManager` can be instantiated with a few arguments: 
+- Resource name, singular and plural,
+- List of enabled operations,
+- Handler
+
+The handler is a class that handles the persistence of entities. It must support **at least** the required methods for the enabled operations.
+
+For example, a resource that wants to enable the `create` operation needs to provide a Handler that has a `Create` method.
+
+The provisioning process is handled by an external `Provisioner` class, but the `ResourceManager` instance handles the actual provisioning, meaning the actual persistence of the provisioning data.
+
+Here is a flow of a `ResourceManager` setup process:
+
+```mermaid
+---
+title: Instantiating a new ResourceManager
+---
+stateDiagram-v2
+
+  Setup: Instantiate ResourceManager
+  
+  app --> Setup
+  Setup --> Registering
+  
+  state Setup {
+    validateHandler: check that \n handler implements \n the registered operations
+    bind: Bind handler methods to http handlers
+    
+    [*] --> validateHandler
+    validateHandler --> bind
+  }
+
+  state Registering {
+    registerRoutes: create mux subrouter \n with http handlers
+    registerProvisioner: add new ResourceManager \n to provisioner registry
+    [*] --> registerRoutes
+    registerRoutes --> registerProvisioner
+  }
+
+```
+

wiki/README.md

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+# Wiki Index
+
+
+## Architecture 
+
+1. [Resource Manager](../server/resourcemanager/README.md)