Add note about line break in call to sed

[EllaKaye]

No description provided.

[aitap]

Interesting. This seems to be done by R Markdown, because the original source code has the command in one line, unwrapped:

rcwg/working_documents/install_r_macos.Rmd

Lines 205 to 207 in 2599e69

	<code>
	sed -i.bak \"s|\\\\$(GIT) svn info|\$TOP_SRCDIR/.github/scripts/svn-info.sh|\" \"\$TOP_SRCDIR/Makefile.in\"
	</code>

It may also be possible to pre-wrap the command, escaping the newlines so that it would still work when copied and pasted into the terminal:

sed -i.bak \
"s|\$(GIT) svn info|$TOP_SRCDIR/.github/scripts/svn-info.sh|" \
"$TOP_SRCDIR/Makefile.in"