Professional documents must be proofread and copy-edited. The best writer can make mistakes and not all of us are nit-picking grammarians. You might ask, “Does it really matter if I skip a comma? Put a semi-colon instead of a colon? Say “alternate” when I mean “alternative”? The answer is YES, it does matter. Because the meaning is changed when punctuation and grammar are incorrect, and what we want is to communicate EXACTLY WHAT WE MEAN. How about this genuine newspaper headline: “Two Soviet Ships Collide – One Dies”. Our reaction is to burst out laughing, but did the journalist mean that?
How do we avoid whoopses like this? By using a good editor to ensure that your documentation is grammatically of the highest standard. This will ensure confidence in your professionalism, both in yourself and your recipient.