added template for Exercism project

Co-Authored-By: Yosef Benny Widyokarsono <fybwid@gmail.com>

community/Exercism.gitignore

@@ -0,0 +1,5 @@
+# gitignore template for Exercism project
+# website: https://exercism.io/
+
+# Ignore .exercism folder which contain sensitive data
+.exercism