Add readme

and update container's alpine

Containerfile

@@ -1,4 +1,4 @@
-ARG alpine_version=3.21
+ARG alpine_version=3.22
 
 FROM docker.io/library/rust:1-alpine${alpine_version} AS builder
 

README.md

@@ -0,0 +1,30 @@
+
+# rvault
+
+rvault is an open-source implementation of the API of Vault and OpenBao, written in Rust.
+
+## Running
+
+You can run an offline build with `SQLX_OFFLINE=true cargo run` or `build`, respectively.
+An offline build requires an up-to-date SQLx preparation.
+
+An OCI container image can be created using `podman build . -t rvault`.
+
+Furthermore, rvault attempts to read a `.env` file in the current working directory.
+For example, its content could be:
+
+```txt
+DATABASE_URL=sqlite:test.db
+RUST_LOG=debug
+```
+
+## Development
+
+SQLx preparation can be updated with `cargo sqlx prep`.
+Hence, it is not useful for development.
+With `cargo sqlx database reset` the database will be recreated,
+deleting all contents and reapplying migrations.
+This is helpful when changing migrations during development.
+
+When running a normal, not-offline, build, the database must be migrated (e.g. using `cargo sqlx database reset`)
+for compilation of compile-time-checked queries.