Add OpenGraph meta tags to the front page

Author: CyberShadow

index.dd

@@ -434,6 +434,7 @@ Macros:
     FRONTPAGE_ORG=$(DIVC frontpage-orgs-cell dont-highlight-link donthyphenate, $(LINK2 $2, $(FRONTPAGE_ORG_IMG $3)) $(H3 $1) $(P $(I $4 )))
     _= Single word inline CSS needs to be escaped _=
     C_A=$1:$2;
+    META_DESCRIPTION=D is a systems programming language with C-like syntax and static typing.
     EXTRA_HEADERS=$(T style,
         .why-d-icon {
             padding-right: 0.2em;
@@ -467,3 +468,10 @@ Macros:
             margin-bottom: -0.5em;
         }
     )
+    $(COMMENT index.html only for now, until we can figure out
+              how to generate a URL to the current page for og:url)
+    <meta property="og:title" content="$(FULL_TITLE)" />
+    <meta property="og:type" content="website" />
+    <meta property="og:url" content="https://dlang.org/" />
+    <meta property="og:image" content="https://dlang.org/images/dlogo_opengraph.png" />
+    <meta property="og:description" content="$(META_DESCRIPTION)" />