Fix monospace render problem in tutorial

According to [documentation](https://docs.asciidoctor.org/asciidoc/latest/text/monospace/)
of AsciiDoc:
As with other types of text formatting, if the text is bounded by
word characters on either side, it must be enclosed in a double
pair of backtick characters (``) in order for the formatting to be
applied.

doc/src/tutorial.adoc

@@ -426,7 +426,7 @@ exe app : app.cpp core ;
 This works no matter what kind of linking is used. When `core` is built as a
 shared library, links `utils` directly into it. Static libraries can't link
 to other libraries, so when `core` is built as a static library, its
-dependency on `utils` is passed along to `core`'s dependents, causing `app`
+dependency on `utils` is passed along to ``core``'s dependents, causing `app`
 to be linked with both `core` and `utils`.
 ====