feat: add MarkdownContent component

.changeset/wet-tools-exercise.md

@@ -0,0 +1,15 @@
+---
+'@backstage/core': minor
+---
+
+Adds the MarkdownContent component to render and display markdown input.
+
+```
+  <MarkdownContent content={markdown} />
+```
+
+Render and display the github flavored markdown [GFM](https://github.github.com/gfm/) input:
+
+```
+ <MarkdownContent content={markdownGithubFlavored} enableGfm />
+```