added esp_mm, esp_psram component description

components/README.md

@@ -102,6 +102,18 @@ Example:
 - `malloc` is implemented in terms of the component `heap`'s functions
 - `gettimeofday` is implemented in terms of system time in `esp_system`
 
+#### `esp_mm`
+
+Memory management. Currently, this encompasses:
+
+- Memory mapping for MMU supported memories
+- Memory synchronisation via Cache
+- Utils such as APIs to convert between virtual address and physical address
+
+#### `esp_psram`
+
+Contains implementation of PSRAM services
+
 #### `esp_system`
 
 Contains implementation of system services and controls system behavior. The implementations