Start working on the control flow graphs post

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

content/blog/06_spa_agda_cfg/while-cfg.dot

@@ -0,0 +1,15 @@
+digraph G {
+    graph[dpi=300 fontsize=14 fontname="Courier New"];
+    node[shape=rectangle style="filled" fillcolor="#fafafa" penwidth=0.5 color="#aaaaaa"];
+    edge[arrowsize=0.3 color="#444444"]
+
+    node_begin [label="x = ...;\l"]
+    node_cond [label="x\l"]
+    node_body [label="x = x - 1\l"]
+    node_end [label="y = x\l"]
+
+    node_begin -> node_cond
+    node_cond -> node_body
+    node_cond -> node_end
+    node_body -> node_cond
+}