[skip ci] fix documentation typos

Found via codespell v1.17.0.dev0  
```
codespell -q 3 -L aci,ake,aline,alle,alledges,alocation,als,ang,anid,ba,beginn,behaviour,bloaded,byteorder,calculater,cancelled,cancelling,cas,cascade,centimetre,childs,colour,colours,commen,connexion,currenty,dof,doubleclick,dum,eiter,elemente,ende,feld,finde,findf,freez,hist,iff,indicies,initialisation,initialise,initialised,initialises,initialisiert,ist,kilometre,lod,mantatory,methode,metres,millimetre,modell,nd,noe,normale,normaly,nto,numer,oder,orgin,orginx,orginy,ot,pard,pres,programm,que,recurrance,rougly,seperator,serie,sinc,strack,substraction,te,thist,thru,tread,uint,unter,vertexes,wallthickness,whitespaces -S ./.git,*.po,*.ts,./ChangeLog.txt,./src/3rdParty,./src/Mod/Assembly/App/opendcm,./src/CXX,./src/zipios++,./src/Base/swig*,./src/Mod/Robot/App/kdl_cp,./src/Mod/Import/App/SCL,./src/WindowsInstaller,./src/Doc/FreeCAD.uml
```

src/Mod/Mesh/App/MeshPy.xml

@@ -469,7 +469,7 @@ an empty dictionary if there is no intersection.
 				<UserDocu>getPlanarSegments(dev,[min faces=0]) -> list
 Get all planes of the mesh as segment.
 In the worst case each triangle can be regarded as single
-plane if none of its neighours is coplanar.</UserDocu>
+plane if none of its neighbors are coplanar.</UserDocu>
 			</Documentation>
 		</Methode>
         <Methode Name="getSegmentsOfType" Const="true">