add a license

3 files changed, 8 insertions, 2 deletions

diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000..431007a
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,2 @@
+[![Creative Commons BY-SA License](https://i.creativecommons.org/l/by-sa/4.0/80x15.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+This work is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/").
diff --git a/README.md b/README.md
index c178d02..dbae295 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
-[project home](https://sr.ht/~boringcactus/crowbar-lang/)
+project home: <https://sr.ht/~boringcactus/crowbar-lang/>
 
-[read the spec](https://man.sr.ht/~boringcactus/crowbar-spec/)
+read the spec: <https://man.sr.ht/~boringcactus/crowbar-spec/>
+
+[![Creative Commons BY-SA License](https://i.creativecommons.org/l/by-sa/4.0/80x15.png)](http://creativecommons.org/licenses/by-sa/4.0/)
diff --git a/index.md b/index.md
index 9fc8512..9fd705a 100644
--- a/index.md
+++ b/index.md
@@ -17,3 +17,5 @@ This is entirely a work-in-progress, and should not be relied upon to be stable
 [Read the Syntax chapter of the spec.](syntax.md)
 
 # Semantics
+
+[![Creative Commons BY-SA License](https://i.creativecommons.org/l/by-sa/4.0/80x15.png)](http://creativecommons.org/licenses/by-sa/4.0/)