merged introduction from concepts section into microservices SDK section

[BeateRixen]

As agreed on in this ticket https://cumulocity.atlassian.net/browse/MTM-61371 we want to move the content of https://cumulocity.com/docs/concepts/applications/ out of the concepts section.

The text in https://cumulocity.com/docs/concepts/applications/#microservices anyway was partly a duplicate of the text in here: https://cumulocity.com/docs/microservice-sdk/general-aspects/#introduction.

I tried to merge the texts into one.

[github-actions]

Preview available here

[BeateRixen]

@rahulc8y @eickler @MWindel Please approve

[eickler]

@rahulc8y @nickponomar-c8y @BeateRixen I leave it to you if you see it in the scope of the PR, but this image in the introduction looks really odd to me, has no relationship to the text before and after, is not explained and has odd interpretation possibilities such as

• Core consists only of API and database.
• "Microservice ... 1" is somehow special compared to "Microservice ... n" and the others.
• There is a link between 1 and the other instances of the microservices.
• There is a link between Microservice B1 and Microservice X1.

I would have expected that this shows a bit about API gateway, tenancy and other functionalities that are discussed around it. We might even just delete it, maybe better no image than a misleading one.

[BeateRixen]

@rahulc8y What is your take on the image? Shall we remove it? Should I wait with merging this PR until the other files in this folder have also been moved and remove the entire section in one go?

[rahulc8y]

@nickponomar Hi Nick, I believe Andre's comments about the image are valid, but this is also more related to microservice hosting, since this isn't my area of expertise, I'd appreciate your review

@rahulc8y What is your take on the image? Shall we remove it? Should I wait with merging this PR until the other files in this folder have also been moved and remove the entire section in one go?

[nickponomar-c8y]

@rahulc8y @nickponomar-c8y @BeateRixen I leave it to you if you see it in the scope of the PR, but this image in the introduction looks really odd to me, has no relationship to the text before and after, is not explained and has odd interpretation possibilities such as

• Core consists only of API and database.
• "Microservice ... 1" is somehow special compared to "Microservice ... n" and the others.
• There is a link between 1 and the other instances of the microservices.
• There is a link between Microservice B1 and Microservice X1.

I would have expected that this shows a bit about API gateway, tenancy and other functionalities that are discussed around it. We might even just delete it, maybe better no image than a misleading one.

I agree, the image is misleading, let's delete it.