vdoc: include the project root folder, when searching for readme of src/ (#19000)

cmd/tools/vdoc/tests/testdata/readme_in_project_root/README.md

@@ -0,0 +1 @@
+hello from readme

cmd/tools/vdoc/tests/testdata/readme_in_project_root/src/main.comments.out

@@ -0,0 +1,3 @@
+module foo
+
+fn bar()

cmd/tools/vdoc/tests/testdata/readme_in_project_root/src/main.readme.comments.out

@@ -0,0 +1,4 @@
+hello from readme
+module foo
+
+fn bar()

cmd/tools/vdoc/tests/testdata/readme_in_project_root/src/main.v

@@ -0,0 +1,3 @@
+module foo
+
+pub fn bar() {}

cmd/tools/vdoc/tests/vdoc_file_test.v

@@ -52,6 +52,11 @@ fn check_path(vexe string, dir string, tests []string) int {
 			cmd: '${os.quoted_path(vexe)} doc -comments ${os.quoted_path(program)}'
 			out_filename: 'main.comments.out'
 		)
+		fails += check_output(
+			program: program
+			cmd: '${os.quoted_path(vexe)} doc -readme -comments ${os.quoted_path(program)}'
+			out_filename: 'main.readme.comments.out'
+		)
 		total_fails += fails
 		if fails == 0 {
 			println(term.green('OK'))

cmd/tools/vdoc/vdoc.v

@@ -233,6 +233,9 @@ fn (vd VDoc) get_readme(path string) string {
 		}
 	}
 	if fname == '' {
+		if path.all_after_last(os.path_separator) == 'src' {
+			return vd.get_readme(path.all_before_last(os.path_separator))
+		}
 		return ''
 	}
 	readme_path := os.join_path(path, '${fname}.md')