Add note on Apostrophe markdown editor

notebook/Mail/Mail Delivery Agent.md

@@ -2,5 +2,5 @@
 aliases: MDA
 ---
 # Mail Delivery Agent
-- Last [[MTA]] to handle a message
+- Last [[Mail Transfer Agent]]s to handle a message
 - Relays the message to the recipient user or stores it for the user to retreive

notebook/Tools/Apostrophe.md

@@ -0,0 +1,13 @@
+# Apostrophe
+> Focus on your writing with a clean, distraction-free markdown editor.
+
+-   An UI tailored to comfortable writing
+-   A distraction-free mode
+-   Dark, light and sepia themes
+-   Everything you expect from a text editor, such as spellchecking or document statistics
+-   Live preview of what you write
+-   Export to all kind of formats: PDF, Word/Libreoffice, LaTeX, or even HTML slideshows
+
+```sh
+flatpak install flathub org.gnome.gitlab.somas.Apostrophe
+```