[rtems-docs commit] Add a cheetsheet link to the README.txt

[Chris Johns]

Module:    rtems-docs
Branch:    master
Commit:    2e6f49f841215080a018c3a17ce8a8e5289b0506
Changeset: http://git.rtems.org/rtems-docs/commit/?id=2e6f49f841215080a018c3a17ce8a8e5289b0506

Author:    Chris Johns <chrisj at rtems.org>
Date:      Thu Feb 21 13:03:07 2019 +1100

Add a cheetsheet link to the README.txt

---

 README.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/README.txt b/README.txt
index ed05fb8..e002f60 100644
--- a/README.txt
+++ b/README.txt
@@ -24,6 +24,10 @@ created is worth it.
 
 Images can be created from source using PlantUML and Ditaa.
 
+A Sphinx checksheet is:
+
+ http://docs.sphinxdocs.com/en/latest/cheatsheet.html#rst-cheat-sheet
+
 Production Quality Hosts
 ------------------------