Fix typos in documentation

Author: per1234

README.adoc

@@ -32,6 +32,6 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 == How-to generate bitmaps from the fonts ==
 [source,bash]
 ----
-cd extra
+cd extras
 ./generate_font.py 5x7.bdf Font_5x7.c Font_5x7
 ----

docs/api.md

@@ -202,7 +202,7 @@ YourScreen.endDraw();
 
 #### Description
 
-Set clear the screen contents, uses the background colour set in background().
+Clear the screen contents, uses the background colour set in background().
 
 #### Syntax
 
@@ -561,7 +561,7 @@ YourScreen.endDraw();
 
 #### Description
 
-Sets the font uses for text. The library current has the Font_4x6 and Font_5x7 built in.
+Sets the font used for text. The library current has the Font_4x6 and Font_5x7 built in.
 
 #### Syntax
 

docs/readme.md

@@ -1,6 +1,6 @@
 # Arduino Graphics Library
 
-This is a library that allows you to draw and write on screens with graphical primitives; it requires a specific hardware interfacce library to drive the screen you are using, therefore every screen type should have its own hardware specific library.
+This is a library that allows you to draw and write on screens with graphical primitives; it requires a specific hardware interface library to drive the screen you are using, therefore every screen type should have its own hardware specific library.
 
 To use this library
 

extras/generate_font.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# This file is part of the MKRRGBMatrix library.
+# This file is part of the ArduinoGraphics library.
 # Copyright (c) 2018 Arduino SA. All rights reserved.
 #
 # This library is free software; you can redistribute it and/or