add the document about update command (#600)

* add the document about update command

* update

docs/guides/renovate.md

@@ -14,6 +14,11 @@ sidebar_position: 10
 
 ![image](https://user-images.githubusercontent.com/13323303/176582627-44f27c48-213b-44da-b18f-d4d482ef2f56.png)
 
+:::info
+As of aqua v2.14.0, you can update them by `aqua update` command too.
+Please see [Update registries and packages by update command](update-command.md) too.
+:::
+
 aqua manages package and registry versions,
 so it is important to update them continuously.
 aqua doesn't provide sub commands like `aqua update` or options like `aqua install --update`.

docs/guides/update-command.md

@@ -0,0 +1,187 @@
+---
+sidebar_position: 300
+---
+
+# Update registries and packages by update command
+
+:::info
+You can update them by Renovate too.
+Please see [Update packages by Renovate](renovate.md) too.
+:::
+
+[#1657](https://github.com/aquaproj/aqua/issues/1657) [#2329](https://github.com/aquaproj/aqua/pull/2329) aqua >= v2.14.0
+
+You can update registries and packages by `aqua update (up)` command.
+
+If no argument is passed, all registries and packages are updated to the latest.
+
+```sh
+# Update all packages and registries to the latest versions
+aqua update
+```
+
+This command has an alias "up"
+
+```sh
+aqua up
+```
+
+This command
+
+- gets the latest version from GitHub Releases, GitHub Tags, and crates.io and updates aqua.yaml
+- doesn't install packages
+
+## Updated configuration file paths
+
+This command finds a configuration file `aqua.yaml` according to [the rule](/docs/reference/config/#configuration-file-path) and updates only one file.
+Once this command finds one file, it stops searching other aqua.yaml.
+
+So if you want to update other files, please change the current directory or specify the configuration file path with the option `-c`.
+
+```sh
+aqua -c foo/aqua.yaml update
+```
+
+## Update only registries
+
+If you want to update only registries, please use the `--only-registry [-r]` option.
+
+```sh
+# Update only registries
+aqua update -r
+```
+
+## Update only packages
+
+If you want to update only packages, please use the `--only-package [-p]` option.
+
+```sh
+# Update only packages
+aqua update -p
+```
+
+## Update only specific commands
+
+You can specify packages with command names. aqua finds packages that have these commands and updates them.
+
+```sh
+aqua update <command name> [<command name> ...]
+```
+
+e.g.
+
+```sh
+# Update cli/cli
+aqua update gh
+```
+
+## Select packages with Fuzzy Finder
+
+If you want to update only specific packages, please use the `-i` option.
+You can select packages with the fuzzy finder.
+If `-i` option is used, registries aren't updated.
+
+```sh
+# Select updated packages with fuzzy finder
+aqua update -i
+```
+
+## Select the package version with Fuzzy Finder
+
+If you want to select versions, please use the `-s` option.
+You can select versions with the fuzzy finder. You can not only update but also downgrade packages.
+
+```sh
+# Select updated packages and versions with fuzzy finder
+aqua update -i -s
+```
+
+## The field `version` is ignored
+
+This command doesn't update packages if the `version` field is used.
+
+```yaml
+packages:
+  - name: cli/[email protected] # Update
+  - name: gohugoio/hugo
+    version: v0.118.0 # Doesn't update
+```
+
+So if you don't want to update specific packages, the `version` field is useful.
+
+## commit hashes are ignored
+
+This command doesn't update commit hashes.
+
+```yaml
+packages:
+  - name: google/pprof@d04f2422c8a17569c14e84da0fae252d9529826b # Doesn't update
+```
+
+## Known Issues
+
+There are some known issues related to the third party library [goccy/go-yaml](https://github.com/goccy/go-yaml).
+
+### `null` is set to `packages` wrongly if registries are updated and `packages` is empty
+
+This issue is because of the third party library [goccy/go-yaml](https://github.com/goccy/go-yaml).
+
+Before
+
+```yaml
+registries:
+- ref: v4.60.0
+  type: standard
+packages:
+```
+
+Run `aqua up`.
+
+```console
+$ aqua up
+INFO[0000] updating a registry                           aqua_version= env=darwin/arm64 new_version=v4.65.0 old_version=v4.60.0 program=aqua registry_name=standard
+```
+
+After
+
+```yaml
+registries:
+- ref: v4.65.0
+  type: standard
+packages: null
+```
+
+### Newlines are removed wrongly
+
+This issue is because of the third party library [goccy/go-yaml](https://github.com/goccy/go-yaml).
+
+- https://github.com/goccy/go-yaml/issues/285
+
+Before
+
+```yaml
+registries:
+- ref: v4.60.0
+  type: standard
+
+
+packages:
+- name: suzuki-shunsuke/[email protected]
+```
+
+Run `aqua up`.
+
+```console
+$ aqua up
+INFO[0000] updating a registry                           aqua_version= env=darwin/arm64 new_version=v4.65.0 old_version=v4.60.0 program=aqua registry_name=standard
+```
+
+After
+
+```yaml
+registries:
+- ref: v4.65.0
+  type: standard
+packages:
+- name: suzuki-shunsuke/[email protected]
+```