Update clipsegment documentation
Update clipsegment documentation

Per the tests here (https://github.com/Leaflet/Leaflet/blob/master/spec/suites/geometry/LineUtilSpec.js), and the implementation, clipSegement no longer modifies the points in place.
tsantacruz/RotationalMarker,davojta/Leaflet,sisou/Leaflet,Ubisense/Leaflet,iOffice/Leaflet,akrzyzanowskino/TeamSE,codeator/Leaflet,scaddenp/Leaflet,Ubisense/Leaflet,frogcat/Leaflet,brah/Leaflet,akrzyzanowskino/TeamSE,msiadak/Leaflet,Leaflet/Leaflet,rlugojr/Leaflet,jasonoverland/Leaflet,jasonoverland/Leaflet,iZucken/Leaflet,Neorth/Leaflet,geoloep/Leaflet,AP-whitehat/Leaflet,Trufi/Leaflet,scaddenp/Leaflet,brah/Leaflet,frogcat/Leaflet,iZucken/Leaflet,sisou/Leaflet,Leaflet/Leaflet,stefanocudini/Leaflet,brah/Leaflet,AP-whitehat/Leaflet,stefanocudini/Leaflet,CapeSepias/Leaflet,rlugojr/Leaflet,Ubisense/Leaflet,sisou/Leaflet,codeator/Leaflet,Neorth/Leaflet,CapeSepias/Leaflet,stefanocudini/Leaflet,tsantacruz/RotationalMarker,geoloep/Leaflet,iOffice/Leaflet,jasonoverland/Leaflet,geoloep/Leaflet,tsantacruz/RotationalMarker,scaddenp/Leaflet,Leaflet/Leaflet,msiadak/Leaflet,codeator/Leaflet,msiadak/Leaflet,akrzyzanowskino/TeamSE,Trufi/Leaflet,Trufi/Leaflet,AP-whitehat/Leaflet,davojta/Leaflet,CapeSepias/Leaflet,rlugojr/Leaflet,iOffice/Leaflet,frogcat/Leaflet,davojta/Leaflet,Neorth/Leaflet,iZucken/Leaflet