Add polish language

Author: KrzysztofPa

README.md

@@ -24,6 +24,7 @@ It may help you to learn what a commit is, why it is important to write good mes
 - [ελληνικά](README_gr-GR.md)
 - [Française](README_fr-FR.md)
 - [پارسی](README_fa-IR.md)
+- [Polish](README_pl-PL.md)
 
 ## What is a "commit"?
 
@@ -263,10 +264,10 @@ This section is a **TL;DR** of Atlassian's excellent tutorial, ["Merging vs. Reb
 
 I particularly prefer to rebase over merge. The reasons include:
 
-* It generates a "clean" history, without unnecessary merge commits
-* _What you see is what you get_, i.e., in a code review all changes come from a specific and entitled commit, avoiding changes hidden in merge commits
-* More merges are resolved by the committer, and every merge change is in a commit with a proper message
-    * It's unusual to dig in and review merge commits, so avoiding them ensures all changes have a commit where they belong
+- It generates a "clean" history, without unnecessary merge commits
+- _What you see is what you get_, i.e., in a code review all changes come from a specific and entitled commit, avoiding changes hidden in merge commits
+- More merges are resolved by the committer, and every merge change is in a commit with a proper message
+  - It's unusual to dig in and review merge commits, so avoiding them ensures all changes have a commit where they belong
 
 ### When to squash