Update O365 deprecation timeline details

Update README coverage with updated details regarding the
deprecation timeline and current plans for v2 and v3 release
series.

refs GH-262

README.md

@@ -18,6 +18,8 @@ A package to send messages to a Microsoft Teams channel.
 - [Features](#features)
 - [Project Status](#project-status)
 - [Supported Releases](#supported-releases)
+ - [Plans: v2](#plans-v2)
+ - [Plans: v3](#plans-v3)
 - [Changelog](#changelog)
 - [Usage](#usage)
  - [Add this project as a dependency](#add-this-project-as-a-dependency)
@@ -120,24 +122,26 @@ For more details, see the
 
 ## Supported Releases
 
-| Series | Example | Status  |
-| -------- | ---------------- | -------------------------------------------- |
-| `v1.x.x` | `v1.3.1` | Not Supported (EOL)  |
-| `v2.x.x` | `v2.6.0` | Supported (until approximately October 2024) |
-| `v3.x.x` | `v3.0.0` | Planning (tentative October 2024) |
-| `v4.x.x` | `v4.0.0-alpha.1` | TBD  |
+| Series | Example | Status |
+| -------- | ---------------- | --------------------------------------- |
+| `v1.x.x` | `v1.3.1` | Not Supported (EOL) |
+| `v2.x.x` | `v2.6.0` | Supported (until approximately 2026-01) |
+| `v3.x.x` | `v3.0.0-alpha.1` | Planning (target 2026-01)  |
+| `v4.x.x` | `v4.0.0-alpha.1` | TBD |
 
-The current plan (now until ~ October 2024):
+### Plans: v2
 
-- continue supporting the v2 branch with bugfixes and minor changes
-- update the v2 branch with support for Power Automate workflow URLs
-- refresh documentation to cover O365 connectors and Power Automate workflow
- connectors
+| Task | Start Date / Version | Status |
+| ------------------------------------------------------------ | -------------------- | -------- |
+| support the v2 branch with bugfixes and minor changes | 2020-03-29 (v2.0.0) | Ongoing |
+| add support & documentation for Power Automate workflow URLs | v2.11.0-alpha.1 | Complete |
 
-Early October 2024:
+### Plans: v3
+
+Early January 2026:
 
 - Microsoft [drops support for O365
- connectors][o365-connector-retirement-announcement] on 2024-10-01
+ connectors][o365-connector-retirement-announcement] in December 2025
 - we release a v3 branch
  - drop support for the [🚫
 deprecated][o365-connector-retirement-announcement] O365 connectors
@@ -190,8 +194,34 @@ Quoting from the microsoft365dev blog:
 > - Wave 2 - effective October 1st, 2024: All connectors within all clouds
 >  will stop working
 
-As noted, Existing O365 connector webhook URLs *should* continue to work until
-2024-10-01.
+[Microsoft later changed some of the
+details][o365-connector-retirement-announcement] regarding the retirement
+timeline of O365 connectors:
+
+> Update 07/23/2024: We understand and appreciate the feedback that customers
+> have shared with us regarding the timeline provided for the migration from
+> Office 365 connectors. We have extended the retirement timeline through
+> December 2025 to provide ample time to migrate to another solution such as
+> Power Automate, an app within Microsoft Teams, or Microsoft Graph. Please
+> see below for more information about the extension:
+>
+> - All existing connectors within all clouds will continue to work until
+>  December 2025, however using connectors beyond December 31, 2024 will
+>  require additional action.
+>  - Connector owners will be required to update the respective URL to post
+>  by December 31st, 2024. At least 90 days prior to the December 31, 2024
+>  deadline, we will send further guidance about making this URL update. If
+>  the URL is not updated by December 31, 2024 the connector will stop
+>  working. This is due to further service hardening updates being
+>  implemented for Office 365 connectors in alignment with Microsoft’s
+>  [Secure Future
+>  Initiative](https://blogs.microsoft.com/blog/2024/05/03/prioritizing-security-above-all-else/)
+> - Starting August 15th, 2024 all new creations should be created using the
+>  Workflows app in Microsoft Teams
+
+Since O365 connectors will likely persist in many environments until the very
+end of the deprecation period this project will [continue to support
+them](#supported-releases) until then alongside Power Automate workflows.
 
 #### Workflow connectors
 
@@ -450,8 +480,8 @@ using either this library or the original project.
  ([de-de](https://docs.microsoft.com/de-de/outlook/actionable-messages/adaptive-card),
  [en-us](https://docs.microsoft.com/en-us/outlook/actionable-messages/adaptive-card))
  - O365 connectors
- ([de-de](https://docs.microsoft.com/de-de/outlook/actionable-messages/send-via-connectors),
- [en-us](https://docs.microsoft.com/en-us/outlook/actionable-messages/send-via-connectors))
+  - [Send via connectors](https://docs.microsoft.com/en-us/outlook/actionable-messages/send-via-connectors))
+  - [Create Incoming Webhooks](https://learn.microsoft.com/en-us/microsoftteams/platform/webhooks-and-connectors/how-to/add-incoming-webhook)
  - [adaptivecards.io](https://adaptivecards.io/designer)
  - [Legacy actionable message card reference][msgcard-ref]
  - Workflow connectors