Document which dependencies must be installed, and which must not - #2234

Changed pages include:

• release/accessibility/index.html - view
• release/addons-and-dependencies/index.html - view
• release/applications/index.html - view
• release/build-tools/index.html - view
• release/code-editors/index.html - view
• release/components/index.html - view
• release/configuring-ember/index.html - view
• release/contributing/index.html - view
• release/ember-inspector/index.html - view
• release/getting-started/index.html - view

There are more changes not included in the list