Fix mistakes on WebIDE How-to card

General note: target audience of this card has almost zero knowledge about git, we should not assume that they will intuitively understand things. This card should guide people step-by-step.

Logical mistakes:

1. Card say first "click Commit" and later say "in is important to commit to a new branch". To late, commit is already on develop branch. People do not read full text, they follow point by point.
2. Mentioning of commit message happens under the picture of new branch creation.
3. Section about committing changes starts with merge request.
4. Card advice to merge from feature branch on fork to develop branch on fork while it should be from feature branch on fork to develop branch on original repository.
5. Text suggest that after creating new branch I should "select Start a new request when you are ready to start the submission process and hit the Commit button." I do not have this step in this workflow, it might be from another way of working.

Technical mistakes:

1. If you open WebIDE being on develop branch you will not end up on master branch, as shown on the screenshot.
2. Some screenshots are too big and dilute/scatter attention from the point. Imho, browser can be made smaller to have larger font and less unnecessary information. New merge request screenshot does not need to have a full screen, at the first step only branches are important.
3. Text mentions Source Control button but there is no such things on screenshots and this is not a common knowledge.

P.s. use arrows or numbers on pictures to indicate buttons and fields