org: more language tooltips in HTML output

* doc/org/spot.css: add tooltips for Python and C++.

doc/org/spot.css

@@ -21,7 +21,9 @@ pre.src{padding-top:8px;border-left-style:solid;border-color:#00adad;overflow:au
 pre.src-hoa{padding-top:8px;border-left-style:solid;border-color:#d70079;overflow:auto}
 pre.example{border-left-style:solid;border-color:#d70079}
 pre.src:before{border:none;border-bottom-style:solid;border-color:#00adad;top:0px;}
-pre.src-hoa:before{content:'HOA';border:none;border-bottom-style:solid;border-color:#d70079;overflow:auto}
+pre.src-python:before{content:'Python'}
+pre.src-C\+\+:before{content:'C++'}
+pre.src-hoa:before{content:'HOA';border-color:#d70079}
 img{max-width:100%}
 @media screen{
 #table-of-contents{position:fixed;right:0em;top:0em;max-width:50%;max-height:80%;overflow:auto;z-index:10}