docs(commit-style): add a message about lower case

Although not clearly mentioned in Conventional Commits spec[1], the
first letter of the description must be lower case to pass the
commitlint check. This is described in the test for subject case[2].

[1]: https://www.conventionalcommits.org/en/v1.0.0/#specification
[2]: https://github.com/conventional-changelog/commitlint/tree/master/%40commitlint/config-conventional#subject-case

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I862382452784319a9ae659a70e49a61d79de6ed2
1 file changed