Vi is giving you a hint about “properly” formatting your commit message.
While there is no specific enforcement of one message style w.r.t. another, “traditionally” Git commit messages are structured this way:
- A short title describing the changeset (usually less than 50-60 characters);
- One blank line;
- A more complete description of the commit, optionally divided in paragraphs with other blank lines.
The last paragraph is usually used for “metadata” entries, like Signed-off-by:
.
So, in your case, Vi is probably warning you that the first line is a a little longer than usual and that you did not leave a blank line after it (I say “probably” because I do not use Vi, so I am not sure about it).