Add a "Changelog" page on extension updates

[maxgerhardt]

The change in the project creation and selection workflow through the project and environment selector in extension version v2.3.0, has left many users baffled and frustrated, as in e.g.

• https://community.platformio.org/t/ide-compiles-wrong-project-file/19399
• https://community.platformio.org/t/platformio-compiles-wrong-projects/19769
• https://community.platformio.org/t/platfromio-not-working/19763/5
• https://community.platformio.org/t/ota-uploads-to-wrong-address/19745/11

4 topics created yesterday and today since the release the day before yesterday.

Of course #2410 is related to that in order to be able to have the old behavior (which was reported buggy by users), but I also think it's important that when these workflow changes occurr, that the extension opens up a page after an update where the critical changes are explained. VSCode already does this every time an update is installed (see e.g. https://code.visualstudio.com/updates/v1_54)

[maxgerhardt]

This occurred again in https://community.platformio.org/t/platformio-tries-to-upload-to-wrong-port-even-if-declared-in-platformio-ini/19989 -- if a user hasn't worked with PlatformIO for a while and suddenly the workflow changes, confusion is bound to happen.

[ivankravets]

Hi @maxgerhardt ,

Please re-test with the pre-release version. See the instructions below:

Have a great holiday season! 🤗 🎄