Update docs about attachment path (#26883) (#26884)

Backport #26883 
This change was caused by #26271, for configuration as below:
```
[attachment]
ENABLE = true
PATH = data/attachments
MAX_SIZE = 100
MAX_FILES = 5
```
Before #26271, the resolved path is ${AppWorkPath}/${attachments.PATH}
(such as `/var/lib/gitea/data/attachments`)
After #26271, the resolved path is ${AppDataPath}/${attachments.PATH}
(such as `/var/lib/gitea/data/data/attachments`)

Fix #26864 Follow
#26271

custom/conf/app.example.ini

@@ -1804,8 +1804,9 @@ LEVEL = Info
 ;; Currently, only `minio` is supported.
 ;SERVE_DIRECT = false
 ;;
-;; Path for attachments. Defaults to `data/attachments` only available when STORAGE_TYPE is `local`
-;PATH = data/attachments
+;; Path for attachments. Defaults to `attachments`. Only available when STORAGE_TYPE is `local`
+;; Relative paths will be resolved to `${AppDataPath}/${attachment.PATH}`
+;PATH = attachments
 ;;
 ;; Minio endpoint to connect only available when STORAGE_TYPE is `minio`
 ;MINIO_ENDPOINT = localhost:9000

docs/content/administration/config-cheat-sheet.en-us.md

@@ -818,7 +818,7 @@ Default templates for project boards:
 - `MAX_FILES`: **5**: Maximum number of attachments that can be uploaded at once.
 - `STORAGE_TYPE`: **local**: Storage type for attachments, `local` for local disk or `minio` for s3 compatible object storage service, default is `local` or other name defined with `[storage.xxx]`
 - `SERVE_DIRECT`: **false**: Allows the storage driver to redirect to authenticated URLs to serve files directly. Currently, only Minio/S3 is supported via signed URLs, local does nothing.
-- `PATH`: **data/attachments**: Path to store attachments only available when STORAGE_TYPE is `local`
+- `PATH`: **attachments**: Path to store attachments only available when STORAGE_TYPE is `local`, relative paths will be resolved to `${AppDataPath}/${attachment.PATH}`.
 - `MINIO_ENDPOINT`: **localhost:9000**: Minio endpoint to connect only available when STORAGE_TYPE is `minio`
 - `MINIO_ACCESS_KEY_ID`: Minio accessKeyID to connect only available when STORAGE_TYPE is `minio`
 - `MINIO_SECRET_ACCESS_KEY`: Minio secretAccessKey to connect only available when STORAGE_TYPE is `minio`

docs/content/administration/config-cheat-sheet.zh-cn.md

@@ -230,7 +230,7 @@ menu:
 - `MAX_SIZE`: 附件最大限制，单位 MB，比如： `4`。
 - `MAX_FILES`: 一次最多上传的附件数量，比如： `5`。
 - `STORAGE_TYPE`: **local**: 附件存储类型，`local` 将存储到本地文件夹， `minio` 将存储到 s3 兼容的对象存储服务中。
-- `PATH`: **data/attachments**: 附件存储路径，仅当 `STORAGE_TYPE` 为 `local` 时有效。
+- `PATH`: **attachments**: 存储附件的路径，仅当 STORAGE_TYPE 为 `local` 时可用。如果是相对路径，将会被解析为 `${AppDataPath}/${attachment.PATH}`.
 - `MINIO_ENDPOINT`: **localhost:9000**: Minio 终端，仅当 `STORAGE_TYPE` 是 `minio` 时有效。
 - `MINIO_ACCESS_KEY_ID`: Minio accessKeyID ，仅当 `STORAGE_TYPE` 是 `minio` 时有效。
 - `MINIO_SECRET_ACCESS_KEY`: Minio secretAccessKey，仅当 `STORAGE_TYPE` 是 `minio` 时有效。