add test document

tests/document.gmi

@@ -0,0 +1,25 @@
+# H1
+## H2
+### H3
+
+=> gemini://geminiprotocol.net
+=> gemini://geminiprotocol.net 1965-01-19
+=> gemini://geminiprotocol.net Gemini
+
+* Listing item 1
+* Listing item 2
+* Listing item 3
+
+```inline code```
+
+``` alt text
+multi
+    line code
+```
+
+> quoted string
+
+paragraph line 1
+paragraph line 2
+
+paragraph 2