[v8.x] Backport more non-breaking changes from master

[edmorley]

The next batch of non-breaking fixes from master, backported to the release/v8 branch:

• Set 'root' in monorepo and create-project's .eslintrc.js (Set 'root' in monorepo and create-project's .eslintrc.js #825)
• Docs: Remove duplicate library preset 'Customizing' section (Remove the copy of Customizing section #843)
• Docs: Remove codacy and codecov (Remove codacy and codecov #872)
• Fix broken links in the docs (Fix broken links in the docs #878)
• Docs: Correct style-loader's sass-loader example (Docs: Correct style-loader's sass-loader example #880)
• Add .npmignore to packages that were missing it (Add .npmignore to packages that were missing it #882)

(There will be some more PRs to follow, so don't release/update docs as soon as this merges.)

[eliperelman]

👍