feat(datasheet): use mustache for doc_template

docs/doc_header.md.mustache

@@ -0,0 +1,19 @@
+---
+title: |
+  ![Tiny Tapeout Logo](pics/ttlogo.png){width=15cm}
+    {{name}} Datasheet
+subtitle: Project Repository [{{repo}}]({{repo}})
+documentclass: scrartcl
+date: \today{}
+geometry: "left=2cm,right=2cm,top=2cm,bottom=2.5cm"
+fontsize: 14pt
+mainfont: Latin Modern Sans
+header-includes:
+- \hypersetup{colorlinks=true,
+          urlcolor=blue,
+          linkcolor=[rgb]{0,0,0.5},
+          allbordercolors={0 0 0},
+          pdfborderstyle={/S/U/W 1} }
+---
+
+\pagebreak