Collapse adjacent blank lines.

Automated clean-up with the following commands in Vim:

    :set autowriteall
    :bufdo 0,/^# / g/^$/d
    :bufdo %! cat -s

Verified changes are only in blank lines with 'git diff
--ignore-blank-lines', which has no output.  Also confirmed no
changes in the HTML output from DocC.

Author: amartini51

Sources/TSPL/TSPL.docc/GuidedTour/AboutSwift.md

@@ -1,5 +1,3 @@
-
-
 # About Swift
 
 Understand the high-level goals of the language.
@@ -50,7 +48,6 @@ and it continues to evolve with new features and capabilities.
 Our goals for Swift are ambitious.
 We can’t wait to see what you create with it.
 
-
 <!--
 This source file is part of the Swift.org open source project
 

Sources/TSPL/TSPL.docc/GuidedTour/Compatibility.md

@@ -1,5 +1,3 @@
-
-
 # Version Compatibility
 
 Learn what functionality is available in older language modes.
@@ -51,7 +49,6 @@ that's divided into multiple frameworks,
 you can migrate your code from Swift 4 to Swift 5.7
 one framework at a time.
 
-
 <!--
 This source file is part of the Swift.org open source project