diff --git a/specs/v0.1.md b/specs/v0.1.md
index d49e0c4..1e10489 100644
--- a/specs/v0.1.md
+++ b/specs/v0.1.md
@@ -277,7 +277,7 @@ A single parameter field.
 | description   | string   | Project description. It is used as introduction at the beginning of the documentation. |
 | title         | [string] | Browser title. |
 | url           | [string] | Public URL to access the API (prefix URL for an endpoint).<br>Example: `"https://api.github.com/v1"` |
-| sampleUrl     | [string] | Public URL to test the API.<br>Example: `"https://playground.github.com/v1"` |
+| sampleUrl     | [string] | Public URL to test the API. In generated web documentation, sampleUrl is set as hosting URL if none provided. <br>Example: `"https://playground.github.com/v1"` |
 | generator     | [[Generator](#generator-object)] | Provides generator informations. |
 | template      | [[Template](#template-object)]   | Template specific settings. |
 | header        | [[Header](#header-object)]       | Additional content for the top of the documentation. |