Fix typo in README tomljson installation instructions (#125)

README.md

diff --git a/README.md b/README.md
index b511f39..167fa1c 100644
--- a/README.md
+++ b/README.md
@@ -96,7 +96,7 @@
 * `tomljson`: Reads a TOML file and outputs its JSON representation.
 
     ```
-    go install github.com/pelletier/go-toml/cmd/tomjson
+    go install github.com/pelletier/go-toml/cmd/tomljson
     tomljson --help
     ```