Created SC1050 (markdown)

SC1050.md

@@ -0,0 +1,27 @@
+## Expected 'then'.
+
+### Problematic code:
+
+```sh
+if true
+  echo "True"
+fi
+```
+
+### Correct code:
+
+```sh
+if true
+then
+  echo "True"
+fi
+```
+### Rationale:
+
+ShellCheck has found an `if` statement that appears to be missing a `then`.
+
+Make sure the `then` exists, and that it is the first word of the line (or immediately preceded by a semicolon).
+
+### Exceptions:
+
+None