Update CONTRIBUTING.md (#128)

fixed syntax typo "exceptable" to "acceptable"

Author: Wesley-Jakob-Gilbert

CONTRIBUTING.md

@@ -12,7 +12,7 @@ Refer to the [README](README.md).
 
 ### Variable Naming
 Not all current code follows the conventions below but these will be followed for future developments. 
-- Maximize the use  of semantic and descriptive variables names (e.g. `faceIndices` not `fcInd` or `fi`). Avoid abbreviations except in cases of industry wide usage. In some cases non-descriptive and short variable names are exceptable for instance vertices (points), faces, edges, colors and logic arrays may be denoted `V`, `F`, `E`, `C`, `L`. Furthermore, if a mathematrical symbol or letter is commonly used for some entity it may be acceptable to use short names e.g. coordinates may be referred to as `X`, `Y` and `Z` and image coordinates of indices may be referred to as `I`, `J` and `K`. 
+- Maximize the use  of semantic and descriptive variables names (e.g. `faceIndices` not `fcInd` or `fi`). Avoid abbreviations except in cases of industry wide usage. In some cases non-descriptive and short variable names are acceptable for instance vertices (points), faces, edges, colors and logic arrays may be denoted `V`, `F`, `E`, `C`, `L`. Furthermore, if a mathematrical symbol or letter is commonly used for some entity it may be acceptable to use short names e.g. coordinates may be referred to as `X`, `Y` and `Z` and image coordinates of indices may be referred to as `I`, `J` and `K`. 
 
 ## Testing
 Proving example files as well as a description of the expected outcomes. This can be in the form of a log file or data file that contain partial solution data.