Use "~~del~~" remarkup style in Phabricator

Summary: Add @20after4's new rule to the Phabricator engine.

Test Plan: Wrote some ~~deleted~~ text.

Reviewers: 20after4, btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1972

src/docs/userguide/remarkup.diviner

@@ -18,7 +18,7 @@ formatting text in Remarkup.
 
 These are inline styles, and can be applied to most text:
 
-  **bold** //italic// ##monospaced## `monospaced`
+  **bold** //italic// ##monospaced## `monospaced` ~~deleted~~
   D123 T123 rX123           # Link to Objects
   {D123} {T123}             # Link to Objects (Full Name)
   {F123}                    # Embed Images
@@ -47,9 +47,10 @@ Format **basic text styles** like this:
   //italic text//
   ##monospaced text##
   `monospaced text`
+  ~~deleted text~~
 
-Those produce **bold text**, //italic text//, ##monospaced text## and
-`monospaced text`, respectively.
+Those produce **bold text**, //italic text//, ##monospaced text##,
+`monospaced text` and ~~deleted text~~, respectively.
 
 = Layout =