Added missing period for consistency and readability

Added a missing period in a specific part of the text to maintain consistency across the document. This ensures a uniform writing style, improves readability, and aligns with the formatting used throughout the content.

CONTRIBUTING.md

@@ -34,7 +34,7 @@ We will start the discussion about the bugs to fix and the features of each rele
 Regarding the release plan, we will release a minor version at the end of every month. Here is some detail.
 
 1. Assume our current stable release is 4.3.0. We will start the discussion of the milestone of the release two versions ahead, which is 4.5.0 at the beginning of each month. At this time, we should also kick off the development of the next release, which is 4.4.0.
-2. Finish 4.4.0 development on about the 22nd of this month and start the testing. And the 4.5.0 milestone discussion is frozen and published on the [GitHub](https://github.com/apache/echarts/milestone/14)
+2. Finish 4.4.0 development on about the 22nd of this month and start the testing. And the 4.5.0 milestone discussion is frozen and published on the [GitHub](https://github.com/apache/echarts/milestone/14).
 3. Vote in the mailing list for the 4.4.0 release at the end of this month.
 
 ## Pull Requests