Improve MD files (with mdl feedback).

Signed-off-by: Felix Fontein <felix@fontein.de>

CONTRIBUTING.md

@@ -3,7 +3,7 @@
 The SOPS project welcomes contributions from everyone. Here are a few guidelines
 and instructions if you are thinking of helping with the development of SOPS.
 
-# Getting started
+## Getting started
 
 - Make sure you have Go 1.19 or greater installed. You can find information on
   how to install Go [here](https://go.dev/doc/install)
@@ -11,21 +11,22 @@ and instructions if you are thinking of helping with the development of SOPS.
 - Run the tests with `make test`. They should all pass.
 - Fork the project on GitHub.
 - Add your fork to Git's remotes:
-  + If you use SSH authentication: `git remote add <your username> git@github.com:<your username>/sops.git`.
-  + Otherwise: `git remote add <your username> https://github.com/<your username>/sops.git`.
+   - If you use SSH authentication:
+     `git remote add <your username> git@github.com:<your username>/sops.git`.
+   - Otherwise: `git remote add <your username> https://github.com/<your username>/sops.git`.
 - Make any changes you want to SOPS, commit them, and push them to your fork.
 - **Create a pull request against `main`**, and a maintainer will come by and
   review your code. They may ask for some changes, and hopefully your
   contribution will be merged!
 
-# Guidelines
+## Guidelines
 
 - Unless it's particularly hard, changes that fix a bug should have a regression
   test to make sure that the bug is not introduced again.
 - New features and changes to existing features should be documented, and, if
   possible, tested.
 
-# Communication
+## Communication
 
 If you need any help contributing to SOPS, several maintainers are on the
 [`#sops-dev` channel](https://cloud-native.slack.com/archives/C059800AJBT) on

docs/release.md

@@ -54,6 +54,7 @@ This configuration is quite sophisticated, and ensures at least the following:
   git checkout main
   git pull
   ```
+
 - [ ] Create a **signed tag** for the release, using the following command:
 
   ```sh

shamir/README.md

@@ -1,3 +1,5 @@
+# Shamir's secret sharing
+
 Forked from [Vault](https://github.com/hashicorp/vault/tree/master/shamir)
 
 ## How it works
@@ -102,7 +104,6 @@ L(x) =
 
 So the polynomial we were looking for is `y = x^2`.
 
-
 ## Splitting a secret
 
 So we have the ability of splitting a function into parts, but in the context