update ttfautohint dependency information

README.md

@@ -16,13 +16,15 @@ pip install -r requirements.txt
 ```
 
 ## Dependencies to generate webfonts
+* ttfautohint
 * sfnt2woff
 * [woff2](https://github.com/google/woff2)
 
 ### Install on MacOS
 ```
 brew tap bramstein/webfonttools
 brew update
+brew install ttfautohint
 brew install bramstein/webfonttools/sfnt2woff
 brew install bramstein/webfonttools/woff2
 
@@ -32,7 +34,7 @@ Install the dependencies with the respective package manager for your distributi
 
 Note : Compiling [woff2](https://github.com/google/woff2) from source is fairly easy with no additional dependencies (other than the included submodules - [brotli](https://github.com/google/brotli), [terryfy](https://github.com/MacPython/terryfy), [esaxx](https://github.com/hillbig/esaxx)).
 #### Debian-based systems (aptitude | apt)
-`apt install woff-tools` (provides `sfnt2woff`)
+`apt install ttfautohint woff-tools`
 
 ## Generating fonts