updated Contributors list

Former-commit-id: 66bc349600c180802858fbdab19d8cf08b34c4fe

README.MD

@@ -103,6 +103,7 @@ See https://github.com/gildas-lormeau/SingleFile/blob/master/privacy.md
 - Japanese translation done by Shitennouji（四天王寺) (https://github.com/Shitennouji)
 - Polish translation done by xesarni (https://github.com/xesarni)
 - Russian translation done by rstp14 (https://github.com/rstp14)
+- Spanish translation done by strel (https://github.com/strel)
 
 ## Code derived from third party projects
 - csstree: https://github.com/csstree/csstree

extension/ui/pages/help.html

@@ -485,6 +485,7 @@
 					<li>Polish translation done by xesarni (<a href="https://github.com/xesarni">GitHub profile</a>)
 					</li>
 					<li>Russian translation done by rstp14 (<a href="https://github.com/rstp14">GitHub profile</a>)</li>
+					<li>Spanish translation done by strel (https://github.com/strel)</li>
 				</ul>
 			</li>
 			<li> <a id="icons">Icons</a>