docs: integrate Vale for documentation linting (#2242)

* added value rules

* resolved errors raised by vale

* added github action

* fixes to github action

* added details in contribution guidelines

* added rule for numbers

* limited checks to errors

docs/styles/docs/Spacing.yml

@@ -0,0 +1,7 @@
+extends: existence
+message: "'%s' should have one space."
+level: error
+nonword: true
+tokens:
+  - '[a-z][.?!] {2,}[A-Z]'
+  - '[a-z][.?!][A-Z]'