Update Meson docs README [skip ci]

Signed-off-by: Kostiantyn Ponomarenko <konstantin.ponomarenko@gmail.com>

docs/README.md

@@ -1,15 +1,40 @@
-# Building the documentation
+# Meson Documentation
 
-1. Get [hotdoc](https://hotdoc.github.io/installing.html) (0.8.9 required)
-1. Run hotdoc in the docs/ directory:
+## Build dependencies
 
-    ../meson/meson.py build/
+Meson uses itself and [hotdoc](https://github.com/hotdoc/hotdoc) for generating documentation.
+
+Minimum required version of hotdoc is *0.8.9*.
+
+Instructions on how to install hotdoc are [here](https://hotdoc.github.io/installing.html).
+
+## Building the documentation
+
+From the Meson repository root dir:
+```
+$ cd docs/
+$ meson built_docs
+$ ninja -C built_docs/ upload
+```
+Now you should be able to open the documentation locally
+```
+built_docs/Meson documentation-doc/html/index.html
+```
 
 ## Upload
 
-We are using the git-upload hotdoc plugin which basically
+Meson uses the git-upload hotdoc plugin which basically
 removes the html pages and replaces with the new content.
 
 You can simply run:
+```
+$ ninja -C built_docs/ upload
+```
+
+## Contributing to the documentation
 
-    ninja -C build/ upload
+Commits that only change documentation should have `[skip ci]` in their commit message, so CI is not run (it is quite slow).
+For example:
+```
+A commit message [skip ci]
+```