Update README and add env name in case of hitting GitHub API limits

Author: khlopko

README.md

@@ -58,6 +58,33 @@ steps:
   run: swift --version
 ```
 
+To request development snapshots, use one of these options:
+
+**Main development snapshot (trunk)**
+
+```yaml
+swift-version: "main-snapshot-2024-08-01"
+```
+
+Or you can omit date to lookup for latest available snapshot (note that you may run into GitHub API limits, 
+which can be avoided if you specify API Token in your project settings)
+
+```yaml
+swift-version: "main-snapshot"
+```
+
+**Specific version development snapshot**
+
+```yaml
+swift-version: "5.7-snapshot-2022-08-30"
+```
+
+If date is ommited, it will lookup for the latest snapshot
+
+```yaml
+swift-version: "5.7-snapshot"
+```
+
 ## Note about versions
 
 This project uses strict semantic versioning to determine what version of Swift to configure. This differs slightly from the official convention used by Swift.

dist/index.js

@@ -536,10 +536,11 @@ class SnapshotResolver {
         }
         if (!Array.isArray(json)) {
             // fail if couldn't get from second try
-            let errorMessage = "Failed to retrive snapshot tags. Please, try again later" +
-                (this.githubClient.hasApiToken()
-                    ? "."
-                    : ", or specify GitHub API token in your project settings to avoid limits.");
+            let errorMessage = "Failed to retrive snapshot tags. Please, try again later.";
+            if (!this.githubClient.hasApiToken()) {
+                errorMessage +=
+                    " To avoid limits specify `API_GITHUB_ACCESS_TOKEN` in your project settings.";
+            }
             throw new Error(errorMessage);
         }
         const tags = json.map((e) => {

src/snapshot-resolver.ts

@@ -85,10 +85,11 @@ export class SnapshotResolver {
     if (!Array.isArray(json)) {
       // fail if couldn't get from second try
       let errorMessage =
-        "Failed to retrive snapshot tags. Please, try again later" +
-        (this.githubClient.hasApiToken()
-          ? "."
-          : ", or specify GitHub API token in your project settings to avoid limits.");
+        "Failed to retrive snapshot tags. Please, try again later.";
+      if (!this.githubClient.hasApiToken()) {
+        errorMessage +=
+          " To avoid limits specify `API_GITHUB_ACCESS_TOKEN` in your project settings.";
+      }
       throw new Error(errorMessage);
     }
     const tags: Tag[] = json.map((e: any) => {