Add link to optipng in textures.md and fix some formatting

TEXTURES.md

@@ -25,7 +25,7 @@ Choose width of 16 and height of 16 for the image size. While higher resolution
 ## Zoom In
 Next, you'll want to zoom in as the canvas is very small at the default zoom level. To do this either use CTRL + mousewheel, +/-, or navigate to the View menu > zoom > zoom in
 
-##Grid
+## Configure Grid
 Now, we'll want to turn on the grid. Open the edit menu and enable the 'show grid' option.
 
 The default grid size is 10 pixels, we want to change it to a 1 pixel grid. Go to the Image menu and choose 'configure grid.
@@ -45,10 +45,10 @@ Once you have finished up a texture and are ready to export it, navigate to the
 
 After clicking 'Export', a menu will appear with a bunch of options checked. Make sure to uncheck all of these options!!! This will drastically reduce the file size from multiple kilobytes to a couple of hundred bytes. Finally click 'Export' one more time.
 
-###Further optimization
-For those running a GNU/linux distribution, you most likely have the 'optipng command available to you.
+###Further optimization with OptiPNG
+For those running a GNU/linux distribution, you most likely have the 'optipng' command available to you. If it does not come with your system by default, the software homepage can be found [here](https://optipng.sourceforge.net/) where you can download and install from source.
 
-Open up the terminal in the directory where your exported texture is located, and run this command
+First, Open up the terminal in the directory where your exported texture is located (or navigate to the directory with the 'cd your/directory/path/to/textures'), then run this command
 ```
 optipng -o7 *.png
 ```