[DOCS] fix css class (openvinotoolkit#24602)

Author: akopytko

docs/sphinx_setup/_static/css/custom.css

@@ -31,8 +31,7 @@ a#wap_dns {display: none;}
     background-repeat: no-repeat;
     background-image: url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 64' aria-labelledby='openvino github' aria-describedby='openvino github' role='img' xmlns:xlink='http://www.w3.org/1999/xlink'%3E%3Ctitle%3EGithub%3C/title%3E%3Cdesc%3EA solid styled icon from Orion Icon Library.%3C/desc%3E%3Cpath d='M32 0a32.021 32.021 0 0 0-10.1 62.4c1.6.3 2.2-.7 2.2-1.5v-6c-8.9 1.9-10.8-3.8-10.8-3.8-1.5-3.7-3.6-4.7-3.6-4.7-2.9-2 .2-1.9.2-1.9 3.2.2 4.9 3.3 4.9 3.3 2.9 4.9 7.5 3.5 9.3 2.7a6.93 6.93 0 0 1 2-4.3c-7.1-.8-14.6-3.6-14.6-15.8a12.27 12.27 0 0 1 3.3-8.6 11.965 11.965 0 0 1 .3-8.5s2.7-.9 8.8 3.3a30.873 30.873 0 0 1 8-1.1 30.292 30.292 0 0 1 8 1.1c6.1-4.1 8.8-3.3 8.8-3.3a11.965 11.965 0 0 1 .3 8.5 12.1 12.1 0 0 1 3.3 8.6c0 12.3-7.5 15-14.6 15.8a7.746 7.746 0 0 1 2.2 5.9v8.8c0 .9.6 1.8 2.2 1.5A32.021 32.021 0 0 0 32 0z' fill='rgb(255, 255, 255)'%3E%3C/path%3E%3Cpath %3E%3C/path%3E%3C/svg%3E ");
 }
-
-svg path {
+.fa-square-github path {
     fill: none;
 }