[gnome-calendar] docs: update CONTRIBUTING.md

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit f19bf803bacfa722af8c570169a59d408bcbfb66
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Fri Feb 23 16:11:36 2018 -0300

    docs: update CONTRIBUTING.md

 CONTRIBUTING.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e295f5c8..873f6d5a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -7,7 +7,8 @@ Please note we have a code of conduct, please follow it in all your interactions
 
 ## Pull Request Process
 
-1. Ensure your code compiles. Run `make` before creating the pull request.
+1. Ensure your code compiles and doesn't break anything. Run `meson test -C <builddir>` before creating
+   the pull request.
 2. If you're adding new API, it must be properly documented.
 3. The commit message is formatted as follows:
    ```
@@ -17,7 +18,7 @@ Please note we have a code of conduct, please follow it in all your interactions
 ‌
    Another one explaining how you solved that.
 ‌
-   <link to the bug ticket>
+   <link to the issue>
    ```
 4. You may merge the pull request in once you have the sign-off of the maintainers, or if you
    do not have permission to do that, you may request the second reviewer to merge it for you.