Rewrite description for URL alias on node/add/*

Problem/Motivation

The current wording is confusing and too long. The proposed solution offers a shortened and clearer text.

Current:
Optionally specify an alternative URL by which this content can be accessed. For example, type "about" when writing an about page. Use a relative path and don't add a trailing slash or the URL alias won't work.

Proposed resolution

Proposed:
The alternative URL for this content. For example, type "about" when creating an about page. Use a relative path without a trailing slash

Remaining tasks

Need a patch with the text change.

User interface changes

The description text for the URL alias field under URL path settings when adding new content.

API changes

None.

Data model changes

None.

Original report by Xilis

Note: This issue is being posted here as an exercise by a participant in the http://drupalladder.org ladder for contributing to core. Please don't do anything with this post. The real issue has already been resolved in Drupal 8. If you would like to try this exercise yourself, visit http://drupalladder.org and click on Drupal Ladder
Current:
Optionally specify an alternative URL by which this content can be accessed. For example, type "about" when writing an about page. Use a relative path and don't add a trailing slash or the URL alias won't work.

Proposed:
The alternative URL for this content. For example, type "about" when creating an about page. Use a relative path without a trailing slash