Add max file size and max request size configuration properties in README.md

Author: jbern0rd

README.md

@@ -15,6 +15,8 @@ To run properly, the iExec Result Proxy requires:
 
 You can configure the iExec Result Proxy with the following properties:
 
+### Main application properties
+
 | Environment variable | Description | Type | Default value |
 | --- | --- | --- | --- |
 | `IEXEC_RESULT_PROXY_PORT` | Server HTTP port of the result proxy. | Positive integer | `13200` |
@@ -30,6 +32,17 @@ You can configure the iExec Result Proxy with the following properties:
 | `IEXEC_IPFS_HOST` | Host to connect to the IPFS node. | String | `127.0.0.1` |
 | `IEXEC_IPFS_PORT` | Server port of the IPFS node. | Positive integer | `5001` |
 
+### Spring web application properties
+
+In addition to the aforementioned properties, it is possible to leverage [Spring Common Application Properties](https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html).
+More specifically, you may want to configure limits of uploadable file sizes.
+In order to do so, you can override the default for the following [Web Properties](https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html#appendix.application-properties.web).
+
+| Environment variable | Description | Type | Default value |
+| --- | --- | --- | --- |
+| `SPRING_SERVLET_MULTIPART_MAX_FILE_SIZE` | Max file size. | String | `1MB` |
+| `SPRING_SERVLET_MULTIPART_MAX_REQUEST_SIZE` | Max request size. | String | `10MB` |
+
 ## Health checks
 
 A health endpoint (`/actuator/health`) is enabled by default and can be accessed on the **IEXEC_RESULT_PROXY_PORT**.