Add position static utilitiy

__tests__/fixtures/tailwind.css

@@ -2365,6 +2365,10 @@ button,
   display: none;
 }
 
+.static {
+  position: static;
+}
+
 .fixed {
   position: fixed;
 }
@@ -5490,6 +5494,10 @@ button,
     display: none;
   }
 
+  .sm\:static {
+    position: static;
+  }
+
   .sm\:fixed {
     position: fixed;
   }
@@ -8616,6 +8624,10 @@ button,
     display: none;
   }
 
+  .md\:static {
+    position: static;
+  }
+
   .md\:fixed {
     position: fixed;
   }
@@ -11742,6 +11754,10 @@ button,
     display: none;
   }
 
+  .lg\:static {
+    position: static;
+  }
+
   .lg\:fixed {
     position: fixed;
   }
@@ -14868,6 +14884,10 @@ button,
     display: none;
   }
 
+  .xl\:static {
+    position: static;
+  }
+
   .xl\:fixed {
     position: fixed;
   }

src/generators/position.js

@@ -2,6 +2,7 @@ import defineClasses from '../util/defineClasses'
 
 export default function() {
   return defineClasses({
+    'static': { position: 'static' },
     'fixed': { position: 'fixed' },
     'absolute': { position: 'absolute' },
     'relative': { position: 'relative' },