[CI/Build] Add markdown linter (#11857)

Signed-off-by: Rafael Vasquez <rafvasq21@gmail.com>

tools/doc-lint.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+pymarkdownlnt scan docs -r

tools/sphinx-lint.sh

@@ -1,3 +0,0 @@
-#!/bin/bash
-
-sphinx-lint --disable trailing-whitespace,missing-final-newline docs