[javascript][client] Add gitignore to template (#7438)

* [javascript][client] add gitignore template file

* [javascript][client] update samples

samples/client/petstore/javascript-promise-es6/.gitignore

@@ -0,0 +1,33 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directory
+node_modules
+
+# Optional npm cache directory
+.npm
+
+# Optional REPL history
+.node_repl_history

samples/client/petstore/javascript-promise-es6/.openapi-generator/FILES

@@ -1,4 +1,5 @@
 .babelrc
+.gitignore
 .travis.yml
 README.md
 docs/AdditionalPropertiesClass.md