Backport of #11074 - v4.x - doc: replace newlines in deprecation with space

Backport of #11074

As it is, each line in the deprecation heading which are wrapped at 80 characters in the *.md files, are shown in different lines. For example

> Stability: 0 - Deprecated: Use
> `Buffer.from(arrayBuffer[, byteOffset [, length]])`
> instead.

is shown in three different lines. This patch replaces the newlines with space characters, so that the output will be in single line.

PR-URL: https://github.com/nodejs/node/pull/11074

Reviewed-By: Anna Henningsen anna@addaleax.net Reviewed-By: Jeremiah Senkpiel fishrock123@rocketmail.com Reviewed-By: Colin Ihrig cjihrig@gmail.com Reviewed-By: Timothy Gu timothygu99@gmail.com Reviewed-By: James M Snell jasnell@gmail.com Reviewed-By: Luigi Pinca luigipinca@gmail.com Reviewed-By: Michaël Zasso targos@protonmail.com

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)