Remove 'alt' text from HTML comments

Author: anenadic

episodes/20-section2-intro.md

@@ -33,9 +33,6 @@ so we should try and employ such practices early on.
 We will also make use of techniques and infrastructure that allow us to do this
 in a scalable, automated and more performant way as our codebase grows.
 
-<--
-alt="Topics on verifying software correctness covered in the current section: testing frameworks, automating and scaling up testing, and code debugging"
--->
 ```mermaid
     flowchart LR
         accDescr {Topics on verifying software correctness covered in the current section: testing frameworks, automating and scaling up testing, and code debugging}

episodes/30-section3-intro.md

@@ -21,10 +21,6 @@ exercises: 0
 In this section, we will take a step back from coding development practices and tools
 and look at the bigger picture of software as a *process* of development.
 
-<!--
-alt="Topics on software engineering process covered in the current section: gathering requirements, software architecture & design, programming paradigms"
--->
-
 ```mermaid
     flowchart LR
         accDescr {Topics on software engineering process covered in the current section: gathering requirements, software architecture & design, programming paradigms}

episodes/50-section5-intro.md

@@ -30,9 +30,6 @@ how the outside world interacts with and makes use of our software,
 how others can interact with ourselves to report issues,
 and the ways we can successfully manage software improvement in response to feedback.
 
-<!--
-alt="Topics on collaborative software development covered in the current section: issue management, project management, agile development"
--->
 ```mermaid
     flowchart LR
         accDescr {Topics on collaborative software development covered in the current section: issue management, project management, agile development}