markdownlint: fix all warnings

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I1f7fc0d4e6959a7b0f77c8f9899ae120889ceb1d
diff --git a/README.md b/README.md
index 2ef0c2e..3f9d7e0 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 
 For a standard release build, you want something like:
 
-```
+```sh
 ./bootstrap.sh
 ./configure --disable-tests
 make
@@ -19,7 +19,7 @@
 
 For a test / debug build, a typical configuration is
 
-```
+```sh
 ./bootstrap.sh
 ./configure --enable-tests --enable-coverage --enable-valgrind
 make