Add .git-blame-ignore-revs

The added `.git-blame-ignore-revs` file can be used with `git blame`
to ignore certain commits when blaming, which is useful
when we want to commit large formatting changes without messing up
the output of `git blame`. Also, by adding this file to the repo
`GitHub` will pick it up automatically and ignore the listed commits.

Usage:
`git blame --ignore-revs-file .git-blame-ignore-revs somefile.ext`
However, it is highly recommended that you configure `git blame`
locally to always ignore the commits specified in
`.git-blame-ignore-revs`. You can do this by running the following
from the repository's root:
`git config blame.ignoreRevsFile .git-blame-ignore-revs`.
From then on, you can just run `git blame somefile.ext` and ignoring
will also work for git porcelains and integrations automatically.

.git-blame-ignore-revs

@@ -0,0 +1,8 @@
+### NOTE
+# Run `git config blame.ignoreRevsFile .git-blame-ignore-revs`
+# from the repository's root to tell `git blame` to ignore
+# the commits below.
+
+# `fourmolize`
+# CommitDate: Wed Nov 20 17:31:16 2024 +0100
+14e82fce8c6f5b29b2018a1d4fc68c7d8ada256a

.github/PULL_REQUEST_TEMPLATE.md

@@ -14,4 +14,5 @@ to the issue. -->
       [versioning process](https://github.com/intersectmbo/cardano-base/blob/master/RELEASING.md#versioning-process).
 - [ ] The version bounds in `.cabal` files for all affected packages are updated.
       **_If you change the bounds in a cabal file, that package itself must have a version increase._** (See [RELEASING.md](https://github.com/intersectmbo/cardano-base/blob/master/RELEASING.md#versioning-process))
+- [ ] Commits that only contain large amounts of formatting changes were added to `.git-blame-ignore-revs`
 - [ ] Self-reviewed the diff

CONTRIBUTING.md

@@ -25,6 +25,25 @@ infrastructure:
 We use trunk based developement. Normal development will branch off of master and be
 merged back to master.
 
+### Recommended `git` configuration
+
+Once you cloned the repository, it is recommended to run the following
+from the repository's root:
+```bash
+git config blame.ignoreRevsFile .git-blame-ignore-revs
+```
+This way `git blame` will ignore the commits specified in the `.git-blame-ignore-revs`
+file. This can come in handy if you want to exclude large commits
+with only formatting changes.
+You can ignore the above however, if you tend to look at `git blame`
+through GitHub. In that case, you don't have to do anything,
+as GitHub will pick up `.git-blame-ignore-revs` automatically and ignore
+the specified commits.
+
+If you want to add further revisions to the `ignore-revs` file,
+just prepend the full commit hash that you want `git blame` to ignore
+and add the commit's title and date as a comment for clarity.
+
 ### Releasing and versioning
 
 Packages from `cardano-base` are released to