posts: move files into date-prefixed directories

Using date prefixes is better for sorting articles at a glance. Using
directories is more uniform if and when I need to add files to go with
an article.

content/posts/2020-07-14-hello-world/index.md

@@ -0,0 +1,48 @@
+---
+title: "Hello World"
+date: 2020-07-14T18:07:56+02:00
+draft: false
+tags:
+  - test
+categories:
+favorite: false
+tikz: true
+---
+
+## Test post please ignore
+
+Hello world, this is just to test the capabilities of [Hugo](https://gohugo.io/)
+
+<!--more-->
+
+### Syntax highlighting
+
+#### Rust
+
+```rust
+fn main() {
+    println!("Hello World!")
+}
+```
+
+#### Shell
+
+```sh
+echo hello world | cut -d' ' -f 1
+```
+
+### TikZJax support
+
+{{% tikz %}}
+  \begin{tikzpicture}
+    \draw (0,0) circle (1in);
+  \end{tikzpicture}
+{{% /tikz %}}
+
+### Spoilers
+
+{{% spoiler "Don't open me" %}}
+Test 2
+
+Test 3
+{{% /spoiler %}}