Skip package-lock.json and yarn.lock in node_modules #431 (#485)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

test/integration/test-fixtures/npm-lock/node_modules/insert-css/readme.markdown

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+# insert-css
+
+insert a string of css into the `<head>`
+
+[![browser support](https://ci.testling.com/substack/insert-css.png)](https://ci.testling.com/substack/insert-css)
+
+# example
+
+``` js
+    var insertCss = require('insert-css');
+    var styleElement = insertCss('body { background:blue; }');
+```
+
+# api
+
+``` js
+    var insertCss = require('insert-css');
+```
+
+## var styleElement = insertCss(css, opts);
+
+Insert some CSS into the page.
+
+* `opts.container` - Which HTMLElement to use as the base mounting point, defaults to
+`document.querySelector('head')`.
+
+* `opts.prepend` - Add the CSS at the top level of the container instead of at the bottom level (default).
+
+This is particullary useful for library creators where you may want your default CSS to be prepended so it
+can be easily overriden by user styles.
+
+# development
+
+## example
+
+``` sh
+npm run example
+```
+
+## test
+
+``` sh
+npm test
+```