Fix MD040 warnings

The following warnings are generated by using markdownlint analysis:
```
MD040/fenced-code-language Fenced code blocks should have a language specified [Context: "```"]
```
Refer to markdown-lint [1] to fix MD040
[1]: https://github.com/updownpress/markdown-lint/blob/master/rules/040-fenced-code-language.md

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I70cd5bc82959df60091985cc75f83558e6fa7b18
diff --git a/README.md b/README.md
index e7b43c3..f988649 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@
 
 For a standard release build, you want something like:
 
-```
+```sh
 meson setup -Dexamples=false -Dtests=disabled builddir
 ninja -C builddir
 ninja -C builddir install
@@ -37,7 +37,7 @@
 
 For a test / debug build, a typical configuration is
 
-```
+```sh
 meson setup -Dtests=enabled builddir
 meson test -C builddir
 ```