[NFC][Gardening] use more approchable language in the changelog

"ye olde days" is quirky, but not very approachable to readers whose first language isn't English. Also, not everyone is familiar with the shell notation.

Co-Authored-By: Anders Bertelrud <[email protected]>

Author: WowbaggersLiquidLunch

CHANGELOG.md

@@ -6,7 +6,7 @@ Swift 5.3.1
 
 * [#2937](https://github.com/apple/swift-package-manager/pull/2937)
 
-  Manifest files can now have any combination of leading line terminators. All [Unicode line terminators](https://www.unicode.org/reports/tr14/) are recognised. Gone are ye olde days when a shebang-like directive must be at the start of file.
+  Manifest files can now have any combination of leading line terminators. All [Unicode line terminators](https://www.unicode.org/reports/tr14/) are recognised. This allows more flexibility in formatting the Package manifest.
 
   [SR-13566](https://bugs.swift.org/browse/SR-13566) The Swift tools version specification in each manifest file now accepts any combination of _horizontal_ whitespace characters between `//` and `swift-tools-version`, if and only if the specified version > 5.3. For example, `//swift-tools-version:5.3.1` and `//		 swift-tools-version:5.4` are valid.