[DOC] Design Doc on showing changes in commands between versions (#523)

* [DOC] Design Doc for command changes between versions

* Update changesInCommandsOverReleases.md

Author: dennisseah

technical-docs/designs/documents/changesInCommands.png

@@ -0,0 +1,80 @@
+# Software Design Document
+
+Reference: Operational Document for command changes over releases<br> Authors:
+Andre Briggs, Dennis Seah
+
+| Revision | Date         | Author      | Remarks                            |
+| -------: | ------------ | ----------- | ---------------------------------- |
+|      0.1 | Apr-05, 2020 | Dennis Seah | Initial Draft                      |
+|      1.0 | Apr-07, 2020 | Dennis Seah | Bump revision up 1.0 after review. |
+
+## 1. Overview
+
+We have a set of document for each command at
+https://catalystcode.github.io/spk/commands. Our users/customers can use this as
+a reference for all commands supported in each release. They also need to know
+the changes in between releases so that they adapt to these changes (if needed)
+accordingly. They can eye-ball for the changes by comparing the document between
+releases; and it is tedious. In this document, we discuss how to generate
+document to show changes between releases.
+
+## 2. Out of Scope
+
+This design shall only target making user experience better by providing
+information on changes in commands between releases based on the artifacts that
+we generated for each releases. that's all the `data*.json` files in
+https://github.com/CatalystCode/spk/tree/master/docs/commands
+
+## 3. Design Details
+
+### 3.1 Data set
+
+We have a `txt` file that contains all the release numbers and master branch.
+https://github.com/CatalystCode/spk/blob/master/docs/commands/releases.txt. We
+know the releases to compare by sorting them in descending order. e.g.
+
+```
+master
+0.6.0
+0.5.8
+0.5.7
+0.5.6
+0.5.5
+```
+
+That's comparing `master` with `0.6.0` release, `0.6.0` release with `0.5.8`
+release, etc.
+
+### 3.2 Comparing releases
+
+We compare two json files for
+
+1. new commands - commands that are in the current and not in previous release.
+1. dropped commands - commands that are in the previous and not in current
+   release.
+1. changes in commands
+   1. new options - options that are added in current release
+   1. dropped options - options that are removed in current release
+   1. changed options - options that are changed in current release. for this
+      design, we only consider change in option alias e.g. `-O --output` to
+      `-o --output`.
+
+### 3.3 Sample Screenshot
+
+<p style="text-align:center">
+<img src="changesInCommands.png" width="600px">
+</p>
+
+## 4. Dependencies
+
+None
+
+## 5. Risks & Mitigation
+
+None
+
+## 6. Documentation
+
+None
+
+\- end -