Update README.md

Author: JoseAntFer

README.md

@@ -1,5 +1,5 @@
 # TriangleMeshDistance
-Header only, single file, simple and efficient C++11 library to compute the signed distance function to a triangle mesh.
+Header only, single file, simple and efficient C++11 library to compute the signed distance function (SDF) to a triangle mesh.
 
 The distance computation to the triangle collection is accelerated with a sphere bounding volume hierarchy. The sign of the distance is resolved with the method presented in *"Generating Signed Distance Fields From Triangle Meshes"* by Bærentzen, Andreas & Aanæs, Henrik. (2002). Assuming triangle normals point outwards from the enclosed volume, the sign of the distance will be positive outside and negative inside.