feat(sdk): Add mapping template upgrade document

docs/mapping_template_upgrade_guide.md

@@ -0,0 +1,97 @@
+# Mapping template upgrade guide
+
+## Workflow of mapping template release
+
+![image](img/mapping-template-workflow.png)
+
+### Development phase
+
+* Allow multiple versions in development phase.
+* Each development version only records the functional changes compared to the previous development version.
+
+### Release phase
+
+* Create the final release version.
+* Merge all change notes (since the last release) into the final release.
+* Remove all development and test versions in directory of mef-sonata/template-upgrade.
+
+## Mapping Template Version Naming Convention
+
+### Version Pattern
+
+{Major}.{Minor}.{Patch}
+
+* Major
+  * Arabic numerals
+  * Consistent with the major version of the Kraken application
+* Minor
+  * Arabic numerals
+* Patch
+  * Letters or numbers
+
+### Version naming convention
+
+#### Development phase
+
+* version ends with suffix snapshot,for example
+  * 1.0.1-snapshot
+  * 1.2.0-snapshot
+
+#### Release phase
+
+Version should not contain letters,for example
+
+* 1.6.0
+* 1.6.1
+* 2.0.0
+
+The following picture explains the rules for version number changes during the development and release phases.
+![mapping-template-mode.png](img/mapping-template-mode.png)
+## When to add a new mapping template release
+
+* Add API Use Case
+* Modify existed API Use Case
+  * Modify user mapping template
+  * Modify mapping target file
+  * Modify API orchestration file
+  * Modify API request validation rule file
+* Other changes
+  * Add/Modify  API spec file
+  * Add/Modify open API spec of supported product
+
+## How to create a mapping template release
+
+1. Create a mapping template release file(e.g. release.1.5.13.yaml)  under directory of mef-sonata/template-upgrade in the module of kraken-java-sdk-mef.
+
+   Here show an example of mapping template release
+
+   ```yaml
+   ---
+   kind: kraken.product.template-upgrade
+   apiVersion: v1
+   metadata:
+     key: kraken.product.template-upgrade.1.5.13
+     name: V1.5.13
+     labels:
+       productSpec: grace
+       productVersion: V1.5.13
+       publishDate: 2024-11-15
+     description: |
+       Make some improvements to order template:
+         add itemTerm in add order template;
+         add expectedCompletionDate in get order template;
+     version: 1
+   ```
+   **Important fields explanation**
+
+   * productSpec: Standard version of one product.Such as grace,haley in LSO SONATA.
+   * productVersion: Release version of mapping template release.
+   * publishDate: Release date of mapping template.
+   * description: Description of all changes in the current release.
+2. Add path of the release file to mef-sonata/product.yaml
+
+   ```yaml
+   spec:
+     componentPaths:
+       - classpath:/mef-sonata/template-upgrade/release.1.5.13.yaml
+   ```