Add index

Co-Authored-By: Allan Nordhøy <epost@anotheragency.no>

doc_markdown_guide.md

@@ -1 +1,29 @@
 # Markdown Guide
+
+**Index**
+ - [The different title levels](#TitleLevels)
+ - [Paragraph formatting](#ParagraphFormatting)
+ - [Link creation](#LinkCreation)
+    + [Anchor creation](#AnchorCreation)
+ - [Display images](#DisplayImages)
+ - [Citation formatting](#CitationFormatting
+ - [Lists](#Lists)
+    + [Ordered](#Ordered)  
+    + [Unordered](#Unordered)
+ - [Tables](#Tables)
+ - [Code segments](#CodeSegments)
+
+Markdown is a markup language from 2004, with many add-ons supporting its function and existence. This guide explores the possibilities and formatting of the language in the context of YunoHost documentation, and not the Markdown language on its own.
+
+Markdown allows formatting of text using tags, in human-readable format; even with formatting. Outside of plaintext editors, a number of specific programs exist. (Markdown on [framalibre.org] (https://framalibre.org/recherche-par-crit-res?keys=markdown)). It is easy to deal with.
+
+## The different title levels <a name="TitleLevels"></a>
+
+Write headlines like this:
+```markdown
+# Level 1
+## Level 2
+### Level 3
+#### Level 4
+##### Level 5
+###### Level 6