Update Robust.Cdn docs for multi-request publishing API.

src/en/server-hosting/setting-up-robust-cdn.md

@@ -235,10 +235,6 @@ If your fork's repository is hosted on GitHub, the easiest way to automatically
 
 This should be everything you need!
 
-```admonish warning
-Actions publishing works by uploading a temporary artifact and having Robust.Cdn download that. While this should work from a private repo there may be additional cost introduced by this, you've been warned.
-```
-
 ### Custom
 
 For people looking to do custom publishing workflows without GitHub actions, please refer to the API reference of the "publish" endpoint.
@@ -319,7 +315,12 @@ Robust.Cdn stores and expects build zips in the `FileDiskPath` directory (`/buil
 
 ## Example reverse proxy configs
 
-You likely want to run Robust.Cdn behind a reverse proxy of some kind. Here are some example configurations for your reverse proxy:
+You likely want to run Robust.Cdn behind a reverse proxy of some kind. There are a few things to make sure of:
+
+* When using multi-request publishing, you should set the maximum client body size to fit the entire client download at once.
+* When using one-shot publishing, you should set the request timeout high enough (usually more than a minute or two).
+
+Here are some example configurations for your reverse proxy:
 
 ### Nginx
 
@@ -334,7 +335,10 @@ location / {
     # High body size to avoid buffering of download request bodies.
     client_body_buffer_size 10M;
     # Increased read timeout to avoid timeouts on the publish API endpoint.
+    # Not strictly necessary for multi-request publishes, but cannot hurt.
     proxy_read_timeout 120s;
+    # Increased max body size for multi-request publishes. Not necessary for oneshot publishes.
+    client_max_body_size 512m;
     # Boilerplate reverse proxy config.
     proxy_set_header   Host $http_host;
     proxy_set_header   X-Real-IP $remote_addr;
@@ -354,6 +358,14 @@ location / {
 
 Increase your reverse proxy's response timeout. In nginx this is controlled via `proxy_read_timeout`.
 
+### Connection errors during publishing (multi-request publish)
+
+Make sure you have your reverse proxy's max body size set high enough to allow 
+
+### 404 not found error on CDN API while publishing
+
+Make sure you are using the latest version of Robust.Cdn. Version 2.2.0 added a new publishing mechanism that is used by the upstream infrastructure.
+
 ## Migration from Robust.Cdn 1.x
 
 If you were hosting an existing installation of Robust.Cdn from before multi-fork/server manifest support was added (1.0), this part of the guide will help you migrate.
@@ -429,6 +441,10 @@ Some API endpoints may require authentication:
 * Fork control endpoints such as publish need `Authorization: Bearer <updateToken>`, with the `UpdateToken` specified in the fork configuration.
 * Endpoints to access server files require Basic authentication if the fork is configured as private.
 
+### Publishing
+
+There are two separate APIs to publish: "one-shot" and "multi-request". The one-shot API is under `/fork/{fork}/publish`, while the multi-request API is under `/fork/{fork}/publish/{start,file,finish}`. We recommend the multi-request publishing API, and it is also what the official publishing scripts use.
+
 ### GET `/fork/{fork}`
 
 Gets a nice human-readable HTML page about the last builds available.
@@ -445,7 +461,9 @@ Gets a JSON list of every server build available for a fork.
 
 ### POST `/fork/{fork}/publish`
 
-Publishes a new version to the CDN. It expects a JSON body with the following information:
+Publishes a new version to the CDN in a single API request. This is as opposed to the "multi-request" API described below. 
+
+It expects a JSON body with the following information:
 
 ```json
 {
@@ -461,6 +479,49 @@ The archive is must be URL to a zip that Robust.Cdn will download containing the
 
 This require authentication.
 
+### POST `/fork/{fork}/publish/start`
+
+Start a new publishing operation that involves multiple subsequent API requests. The initial JSON request body is as follows:
+
+```json
+{
+  "version": "<version>",
+  "engineVersion": "<engine version>"
+}
+```
+
+The version is the new version number you are publishing. This can be anything. Engine version is the version number of the engine to use.
+
+If a publish is already undergoing on under the given version number, it is aborted and you are given a clean slate.
+
+This require authentication.
+
+### POST `/fork/{fork}/publish/file`
+
+Add an extra file to an in-progress publish.
+
+The file contents are provided in the request body as `application/octet-stream`. Additional metadata should be provided in the following HTTP headers:
+* `Robust-Cdn-Publish-File`: the name of the file being published. Usually this is something like `SS14.Client.zip` or `SS14.Server_win-x64.zip`.
+* `Robust-Cdn-Publish-Version`: the version number being published to (provided before).
+
+This require authentication.
+
+### POST `/fork/{fork}/publish/finish`
+
+Finishes publishing a new version started before.
+
+```json
+{
+  "version": "<version>"
+}
+```
+
+The version is the new version number you are publishing.
+
+If the publish fails validation (for example, missing client files), the publish will be aborted and must be restarted from zero.
+
+This require authentication.
+
 ### POST & OPTIONS `/fork/{fork}/version/{version}/download`
 
 Client CDN download endpoint for a version. See [Delta Updates](../other-projects/launcher/delta-updates-and-manifests.md) for details.