Table 2. Available props 
Table 3. Available props

At this poin in the doc, this is unclear how to configure these props.
This is somewhat clarified starting with the Headline example.
For consistency the examples should contain the props lines. (edited) 
3:26

           importName: MarkdownCard

is inside the Markdown section. For consistency it should have its own section.
3:28

12.2. Defining the layout of the Red Hat Developer Hub Home page

In the entire section, we have the same code blocks indentation issue. For readability all code blocks should be indented properly (+ continuation list)
3:29

13.2. Using a dedicated service to provide data to the Quick access card

In the Verification section, the last code block is missing indentation.
3:31

 12. Customizing the Home page

The assembly introduction could also benefit from the changes in 12.1. Customizing the Home page cards
3:32

11.12. Custom component options for your Developer Hub instance

Is not modularized (should be a procedure)
3:34

11.10.2. Default Backstage page themes

This is a reference module, but it contains steps that belong to a procedure. Consider modularizing into a procedure.
3:34

 11.10.1. Default Backstage theme color palette

Same
3:34

11.9.1. Default Red Hat Developer Hub theme color palette

Same
3:35

11.8. Customizing the font for your Developer Hub instance

Not modularized (should be a procedure)
3:35

 11.6. Customizing the theme mode color palettes for your Developer Hub instance

3:35
Same
3:36

 11.3.3. Modifying or adding a custom menu items for your Developer Hub instance

Remove callouts for AEM migration.
3:36

11.3.2. Configuring a dynamic plugin menu item for your Developer Hub instance

Same
3:37

11.3.1. Customizing the sidebar menu items for your Developer Hub instance

Indentation mission + remove the example title for AEM migration.
3:38

11.2. Customizing the branding logo of your Developer Hub instance

Modularization + remove callouts
3:38

11.1. Customizing the theme mode for your Developer Hub instance

It looks weird to start a module with an admonition
3:39

9.2.1. Disabling the Quickstart plugin

Modularization (procedure)
3:40

9.2. Customizing your Red Hat Developer Hub Quickstart

Remove callouts + example tittle for AEM
3:40

8.1. Configuring a floating action button as a dynamic plugin

Same
3:41

7.6. Quicklinks and Starred Items in the global header

For consitency, use description list
3:41

7.5. Displaying the preferred username in the profile dropdown

Modularization (procedure) + remove example titles (edited) 
3:42

7.3. Configuring the logo in the global header

Admonition indentation
3:43

7.2. Mount points for dynamic plugin integration

Modularization (procedure) + remove example titles
3:43

7.1. Customizing your Red Hat Developer Hub global header

Remove callouts + example tittle for AEM
3:43

6.3. Customizing the Learning Paths by using a customization service

Remove callouts
3:44

5.4. Searching and Filtering Software Catalog items by using the Filter field

Missing intro
3:45

5.3. Searching and Filtering Software Catalogs by Kind

Same
3:47

5. About Software Catalogs

There is only one Software Catalog. It contain catalog items. Therefore we the plural form is inaccurate. "About the Software Catalog" is correct. Replace any "Software Catalogs" (plural) occurrence by "Software Catalog" (singular). (edited) 
 
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4.6. Versioning a Software Template in Red Hat Developer Hub

Example indentation is missing
3:49

4.5. Importing an existing Software Template to Red Hat Developer Hub

Remove callouts for AEM
3:49

4.3. Creating a new software component using Software Templates

Images indentation