docs: update readme

Signed-off-by: jolheiser <john.olheiser@gmail.com>

README.md

@@ -2,6 +2,36 @@
 
 This is a Go port of [git-agecrypt](https://github.com/vlaci/git-agecrypt) with some slight modifications.
 
+Echoed from the original project:
+
+> ## Why should I use this?
+>
+> Short answer: you probably shouldn't. Before considering this approach, take a look at [SOPS](https://github.com/mozilla/sops) and [Hashicorp Vault](https://www.vaultproject.io/) if they are better suited for the problem at hand. **They have a clear security advantage** over `git-age`.
+> 
+> The one use-case where it makes sense to use `git-age` instead is when you want to keep some files secret on a (potentially public) git remote, but you need to have the plaintext in the local working tree because you cannot hook into the above tools for your workflow. **Being lazy is not an excuse to use this software.**
+
+## Install
+
+1. Install `git-age` in your `PATH`
+2. `git age init`
+3. Add some identities
+  - `git age ident key.txt`
+  - `git age ident ssh`
+4. Set up your config ([example](.git-age.yaml))
+5. Use git like normal.
+
+## Decrypting an existing repository
+
+Similar to initial install, adding identities prior to `init` so that any encrypted files are decrypted during initialization.
+
+1. Install `git-age` in your `PATH`
+2. Clone the repository
+3. Add some identities
+  - `git age ident key.txt`
+  - `git age ident ssh`
+4. `git age init`
+5. Use git like normal
+
 ## License
 
 This software was written based off of [git-agecrypt](https://github.com/vlaci/git-agecrypt/tree/945b80556d8848f6e85a8cc0053f9020bdc8b359).