Update release process docs

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

RELEASE_PROCESS.md

@@ -1,10 +1,35 @@
 # How to make a new release
 
-- Update the version number and all the references to it
-- Make a new release on GitHub (i.e. add a new git tag)
-- Publish crates in order:
-  1. `phf_shared`
-  2. `phf_generator`
-  3. `phf_codegen`
-  4. `phf_macros`
-  5. `phf`
+Since v0.11.1, this repository uses [`cargo-smart-release`](https://crates.io/crates/cargo-smart-release) to release crates.
+
+## Installation
+
+```sh
+cargo install cargo-smart-release
+```
+
+## Before running `cargo-smart-release`
+
+If the next version has a major change or bumps MSRV, i.e. it increases a minor version on `v0.Y.Z` or a major version on `vX.Y.Z`,
+update the versions mentioned on the README and doc comments (and CI config if it touches MSRV).
+
+## Run `cargo-smart-release`
+
+First, just run:
+
+```sh
+cargo smart-release phf phf_codegen phf_generator phf_macros phf_shared
+```
+
+This would show what `cargo-smart-release` would do, e.g. how it updates the version number, changelog, etc.
+If you satisfy the output, run:
+
+```sh
+cargo smart-release -u -e phf phf_codegen phf_generator phf_macros phf_shared
+```
+
+This would make actual releases. `-e` means that it executes actual releases and `-u` means that it always updates crates-index.
+`cargo-smart-release` also takes care of the Git tags.
+
+After executing it, ensure that all the releases are actually happened and the tags are pushed.
+If all the things are fine, that's it!