Changed Appsettings.json Secret(s) Missing S (microsoft#551)

Changed Appsetting.json to more accurately reflect dotnet commands user
must type.

samples/apps/copilot-chat-app/webapi/appsettings.json

@@ -29,12 +29,12 @@
     //  - Set AIService to "AzureOpenAI"
     //  - Set DeploymentOrModelId to the name of the deployment to use (e.g., "gpt-35-turbo", "gpt-4", etc.)
     //  - Set Endpoint to the endpoint of your Azure OpenAI instance (e.g., "https://contoso.openai.azure.com")
-    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secret set "Completion:Key" "MY_AZURE_OPENAI_KEY")
+    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secrets set "Completion:Key" "MY_AZURE_OPENAI_KEY")
     // 
     // To use OpenAI as the AI completion service:
     //  - Set AIService to "OpenAI"
     //  - Set DeploymentOrModelId to the name of the deployment to use (e.g., "gpt-3.5-turbo", "gpt-4", etc.)
-    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secret set "Completion:Key" "MY_OPENAI")
+    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secrets set "Completion:Key" "MY_OPENAI")
     //
     "Label": "Completion",
     "AIService": "AzureOpenAI", 
@@ -51,12 +51,12 @@
     //  - Set AIService" to "AzureOpenAI"
     //  - Set DeploymentOrModelId" to the name of the deployment to use (e.g., "text-embedding-ada-002")
     //  - Set Endpoint" to the endpoint of your Azure OpenAI instance (e.g., "https://contoso.openai.azure.com")
-    //  - Set Key" using dotnet's user secrets (see above) (i.e. dotnet user-secret set "Embedding:Key" "MY_AZURE_OPENAI_KEY")
+    //  - Set Key" using dotnet's user secrets (see above) (i.e. dotnet user-secrets set "Embedding:Key" "MY_AZURE_OPENAI_KEY")
     // 
     // To use OpenAI as the AI embedding service:
     //  - Set AIService to "OpenAI"
     //  - Set DeploymentOrModelId to the name of the deployment to use (e.g., "text-embedding-ada-002" )
-    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secret set "Embedding:Key" "MY_OPENAI")
+    //  - Set Key using dotnet's user secrets (see above) (i.e. dotnet user-secrets set "Embedding:Key" "MY_OPENAI")
     //
     "Label": "Embeddings",
     "AIService": "AzureOpenAI",
@@ -68,7 +68,7 @@
   "AzureSpeech": {
     //
     // - Set the Region to the region of your Azure Speech resource (e.g., "westus").
-    // - Set the Key using dotnet's user secrets (see above) (i.e. dotnet user-secret set "AzureSpeech:Key" "MY_AZURE_SPEECH_KEY")
+    // - Set the Key using dotnet's user secrets (see above) (i.e. dotnet user-secrets set "AzureSpeech:Key" "MY_AZURE_SPEECH_KEY")
     // 
     "Label": "AzureSpeech",
     "Region": ""