Minor updates to 4.iii and 4.iv

Updates to improve consistency and describe rationale for version number scheme.

Author: gcharters

docs/howto-update-for-was-fixpack.md

@@ -41,7 +41,7 @@ Please follow sections below in order to update the solution for next tWAS fixpa
       * Click to open the offer for `<date>-twas-cluster-base-image` base image
       * Click `Plan overview` the click to open the plan 
       * Click `Technical configuration` 
-      * Click `+ Add VM image` > Specify a new value for `Disk version`, following the convention \<product version\>.\<date\>, e.g. 9.0.20210929 and write it down 
+      * Click `+ Add VM image` > Specify a new value for `Disk version`, following the convention \<major version\>.YYYYMMDD, e.g. 9.0.20210929 and write it down (We deliberately do not specify the minor verson because the pipeline gets the latest at the time it is run). 
       * Select `SAS URI` > Copy and paste value of `osDiskSasUrl` for `twas-nd` from the github issue for the update to the textbox `SAS URI` 
       * Click `+ Add data disk (max 16)` > Select `Data disk 0` > Copy and paste value of `dataDiskSasUrl` for `twas-nd` from the github issue for the update to the textbox `Data disk VHD link`
       * Scroll to the bottom of the page and click `Save draft`
@@ -53,7 +53,8 @@ Please follow sections below in order to update the solution for next tWAS fixpa
       * Click to open the offer for `ihs base image` 
       * Click `Plan overview` and click to open the plan
       * Click `Technical configuration`
-      * Click `+ Add VM image` > Specify a new value for `Disk version` and write it down > Select `SAS URI` > Copy and paste value of `osDiskSasUrl` for `ihs` from the github issue for the update to the textbox `SAS URI`
+      * Click `+ Add VM image` > Specify a new value for `Disk version`, following the convention \<major version\>.YYYYMMDD, e.g. 9.0.20210929 and write it down (We deliberately do not specify the minor verson because the pipeline gets the latest at the time it is run). 
+      * Select `SAS URI` > Copy and paste value of `osDiskSasUrl` for `ihs` from the github issue for the update to the textbox `SAS URI`
       * Click `+ Add data disk (max 16)` > Select `Data disk 0` > Copy and paste value of `dataDiskSasUrl` for `ihs` from the github issue for the update to the textbox `Data disk VHD link`
       * Scroll to the bottom of the page and click `Save draft`
       * Click `Review and publish`