Explained about missing characters

Home.md

@@ -90,7 +90,13 @@ Issues: [#291](https://github.com/tonsky/FiraCode/issues/291)
 
 Consult [CHANGELOG](https://github.com/tonsky/FiraCode/blob/master/CHANGELOG.md) to see when it was last updated.
 
-#### 4. Check the list of known issues below ↓
+#### 4. Characters look weird, not monospaced, not rendered at all
+
+Some Unicode characters are not in Fira Code. You can start by checking [Fira Mono doc](https://github.com/bBoxType/FiraSans/raw/master/Fira_Mono_3_2/PDF/FiraMono-Regular.otf.pdf) and [Fira Code Changelog](https://github.com/tonsky/FiraCode/blob/master/CHANGELOG.md).
+
+If character is missing, you’ll see glyphs from a fallback font chosen by your system, which might have drastically different look and metrics. Create an issue and I’ll try to add it to the Fira Code in the next version.
+
+#### 5. Check the list of known issues below ↓
 
 ### Known issues