Small improvements in macOS build instructions

Bettered the brew installation to avoid  warnings and added the fact one could generate docs. Only figured that out from scouring the docs

copying.md

@@ -135,6 +135,7 @@ _the openage authors_ are:
 | Ayxan Haqverdili            | Ayxan13                     | aykhanhagverdili à gmail dawt com                 |
 | David Heidelberg            | okias                       | david à ixit dawt cz                              |
 | Giacomo Frascarelli         | 0ro8lu                      | giacomo dawt frascarelli1 à gmail dawt com        |
+| Antonio M. R. Cunha         | Grubben                     | antoniomsprc à gmail dawt com                     |
 
 If you're a first-time committer, add yourself to the above list. This is not
 just for legal reasons, but also to keep an overview of all those nicknames.

doc/build_instructions/os_x_10.14_mojave.md

@@ -7,18 +7,27 @@
 ```
 brew update-reset && brew update
 brew tap homebrew/cask-fonts
-brew cask install font-dejavu-sans
+brew install --cask font-dejavu-sans
 brew install cmake python3 libepoxy freetype fontconfig harfbuzz sdl2 sdl2_image opus opusfile qt5 libogg libpng eigen
 brew install llvm
 pip3 install cython numpy jinja2 lz4 pillow pygments toml
 ```
+Install this **optionally** to later generate the documentation
 
 You will also need [nyan](https://github.com/SFTtech/nyan/blob/master/doc/building.md) and its dependencies:
 
 ```
 brew install flex make
 ```
 
+(For noobs
+## Clone the repository
+```
+git clone https://github.com/SFTtech/openage
+cd openage
+```
+)
+
 ## Building
 
 ```
@@ -30,3 +39,7 @@ make
 
 ## Running
 `make run` or `./bin/run` launches the game. Try `./bin/run --help`!
+
+## To create the documentation
+`make doc`
+For more options and details, refer to [doc/README.md][/doc/README.md]