Auto merge of #10417 - davidpaulmcintyre:cargo-test-doc, r=alexcrichton

Documentation change to cargo-test.md

i added helpful links in the src/man/carg-test.md to show reader how to write unit/integration tests.

i made change to source at src/doc/man/cargo-test.md, then ran
mdbook serve
./build-man.sh
cargo fmt —all

i tested links by viewing md page and its linked pages using mdbook serve

<img width="960" alt="Screen Shot 2022-02-23 at 5 03 31 PM" src="https://user-images.githubusercontent.com/10999581/155435822-f4784513-5b0f-4e2c-8cf1-ede613f64e15.png">

src/doc/man/cargo-test.md

@@ -178,4 +178,4 @@ includes an option to control the number of threads used:
        cargo test --test int_test_name -- modname::test_name
 
 ## SEE ALSO
-{{man "cargo" 1}}, {{man "cargo-bench" 1}}
+{{man "cargo" 1}}, {{man "cargo-bench" 1}}, [types of tests](../reference/cargo-targets.html#tests), [how to write tests](https://doc.rust-lang.org/rustc/tests/index.html)

src/doc/man/generated_txt/cargo-test.txt

@@ -407,5 +407,7 @@ EXAMPLES
               cargo test --test int_test_name -- modname::test_name
 
 SEE ALSO
-       cargo(1), cargo-bench(1)
+       cargo(1), cargo-bench(1), types of tests
+       <https://doc.rust-lang.org/cargo/reference/cargo-targets.html#tests>,
+       how to write tests <https://doc.rust-lang.org/rustc/tests/index.html>
 

src/doc/src/commands/cargo-test.md

@@ -491,4 +491,4 @@ details on environment variables that Cargo reads.
        cargo test --test int_test_name -- modname::test_name
 
 ## SEE ALSO
-[cargo(1)](cargo.html), [cargo-bench(1)](cargo-bench.html)
+[cargo(1)](cargo.html), [cargo-bench(1)](cargo-bench.html), [types of tests](../reference/cargo-targets.html#tests), [how to write tests](https://doc.rust-lang.org/rustc/tests/index.html)

src/etc/man/cargo-test.1

@@ -529,4 +529,4 @@ cargo test \-\-test int_test_name \-\- modname::test_name
 .RE
 .RE
 .SH "SEE ALSO"
-\fBcargo\fR(1), \fBcargo\-bench\fR(1)
+\fBcargo\fR(1), \fBcargo\-bench\fR(1), \fItypes of tests\fR <https://doc.rust\-lang.org/cargo/reference/cargo\-targets.html#tests>, \fIhow to write tests\fR <https://doc.rust\-lang.org/rustc/tests/index.html>