The Economist’s style guide is back online!
Following this style guide will make your documentation successful. Up to you if your software is as well.
Example of brevity from the style guide:
Passive
Be direct. Use the active tense. A hit B describes the event more concisely than B was hit by A.
Compare The Chicago Manual of Style (15th edition) at a 1/3 of a page or The Hodges Harbrace Handbook (17th edition) at 3 pages. Both have amusing examples and details but sometimes you just want the bare rule.