Add .git-blame-ignore-revs

Author: JimBobSquarePants

Diff for: .git-blame-ignore-revs

@@ -0,0 +1,4 @@
+# file-scoped namespaces and global usings
+5528a2923ccc63d776c91994b0b17a2c3ad5be94
+d14c82023fc01a6fca99c42212cb3c97991fae9e
+0e9a066195a100ae56b4ca49cee9927fb15e1482

Diff for: README.md

@@ -77,6 +77,12 @@ To clone ImageSharp locally, click the "Clone in [YOUR_OS]" button above or run
 git clone https://github.com/SixLabors/ImageSharp
 ```
 
+Then set the following config to ensure blame commands ignore mass reformatting commits.
+
+```bash
+git config blame.ignoreRevsFile .git-blame-ignore-revs
+```
+
 If working with Windows please ensure that you have enabled long file paths in git (run as Administrator).
 
 ```bash