Update collapsible navbar docs
Update collapsible navbar docs

- Add .text-muted for text color control over .bg-inverse in the examples
- Add a dark navbar collapse example

Scoutski/bootstrap,SweetProcess/bootstrap,m5o/bootstrap,realcrowd/bootstrap,gijsbotje/bootstrap,Lyricalz/bootstrap,bootstrapbrasil/bootstrap,SweetProcess/bootstrap,vsn4ik/bootstrap,lipis/bootstrap,edanbarak/bootstrap,igoynawamreh/bootstrap,copperdesign/bootstrap,inway/bootstrap,Lyricalz/bootstrap,realcrowd/bootstrap,seanwu99/bootstrap,zalog/bootstrap,peterblazejewicz/bootstrap,igoynawamreh/bootstrap,Hemphill/bootstrap-docs,IdanCo/bootstrap,sealocal/bootstrap,Delagen/bootstrap,lemuelbarango/bootstrap,seanwu99/bootstrap,bardiharborow/bootstrap,janseliger/bootstrap,JumpLinkNetwork/bootstrap-backward,jipexu/bootstrap,zalog/bootstrap,JumpLinkNetwork/bootstrap-backward,nice-fungal/bootstrap,9-chirno/chirno,lipis/bootstrap,sealocal/bootstrap,supergibbs/bootstrap,tomlutzenberger/bootstrap,seanwu99/bootstrap,stanwmusic/bootstrap,inway/bootstrap,hebbet/bootstrap,gijsbotje/bootstrap,Delagen/bootstrap,igoynawamreh/bootstrap,igoynawamreh/bootstrap,tagliala/bootstrap,supergibbs/bootstrap,johnajacob/bootstrap,IdanCo/bootstrap,TheFridayInstitute/bootstrap,johnajacob/bootstrap,andresgalante/bootstrap,afuno/bootstrap,yuyokk/bootstrap,kvlsrg/bootstrap,JumpLinkNetwork/bootstrap-backward,m5o/bootstrap,JumpLinkNetwork/bootstrap-backward,creativewebjp/bootstrap,davethegr8/bootstrap,joblocal/bootstrap,bardiharborow/bootstrap,lemuelbarango/bootstrap,tagliala/bootstrap,fschumann1211/bootstrap,andresgalante/bootstrap,creativewebjp/bootstrap,copperdesign/bootstrap,Scoutski/bootstrap,joblocal/bootstrap,Delagen/bootstrap,n054/bootstrap,abvalentine/bootstrap,janseliger/bootstrap,tibo66/bootstrap,tjkohli/bootstrap,vsn4ik/bootstrap,stanwmusic/bootstrap,creativewebjp/bootstrap,fschumann1211/bootstrap,Hemphill/bootstrap-docs,copperdesign/bootstrap,NCARB/bootstrap,coliff/bootstrap,Hemphill/bootstrap-docs,tibo66/bootstrap,bardiharborow/bootstrap,stanwmusic/bootstrap,tomlutzenberger/bootstrap,yuyokk/bootstrap,yuyokk/bootstrap,n054/bootstrap,tibo66/bootstrap,edanbarak/bootstrap,janseliger/bootstrap,creativewebjp/bootstrap,xt0rted/bootstrap,TheFridayInstitute/bootstrap,Scoutski/bootstrap,johnajacob/bootstrap,jipexu/bootstrap,realcrowd/bootstrap,tjkohli/bootstrap,jipexu/bootstrap,zalog/bootstrap,NCARB/bootstrap,Lyricalz/bootstrap,lipis/bootstrap,supergibbs/bootstrap,afuno/bootstrap,afuno/bootstrap,IdanCo/bootstrap,peterblazejewicz/bootstrap,fschumann1211/bootstrap,GerHobbelt/bootstrap,davethegr8/bootstrap,tagliala/bootstrap,bardiharborow/bootstrap,Delagen/bootstrap,TheFridayInstitute/bootstrap,gijsbotje/bootstrap,hebbet/bootstrap,peterblazejewicz/bootstrap,SweetProcess/bootstrap,realcrowd/bootstrap,IdanCo/bootstrap,jipexu/bootstrap,twbs/bootstrap,joblocal/bootstrap,kvlsrg/bootstrap,tibo66/bootstrap,slavanga/bootstrap,9-chirno/chirno,bootstrapbrasil/bootstrap,fschumann1211/bootstrap,lipis/bootstrap,hebbet/bootstrap,sealocal/bootstrap,johnajacob/bootstrap,xt0rted/bootstrap,seanwu99/bootstrap,coliff/bootstrap,9-chirno/chirno,kvlsrg/bootstrap,TheFridayInstitute/bootstrap,n054/bootstrap,GerHobbelt/bootstrap,NCARB/bootstrap,sealocal/bootstrap,stanwmusic/bootstrap,NCARB/bootstrap,Scoutski/bootstrap,abvalentine/bootstrap,abvalentine/bootstrap,lemuelbarango/bootstrap,vsn4ik/bootstrap,hebbet/bootstrap,slavanga/bootstrap,slavanga/bootstrap,davethegr8/bootstrap,9-chirno/chirno,vsn4ik/bootstrap,afuno/bootstrap,yuyokk/bootstrap,xt0rted/bootstrap,edanbarak/bootstrap,copperdesign/bootstrap,janseliger/bootstrap,nice-fungal/bootstrap,bootstrapbrasil/bootstrap,edanbarak/bootstrap,xt0rted/bootstrap,davethegr8/bootstrap,slavanga/bootstrap,inway/bootstrap,nice-fungal/bootstrap,gijsbotje/bootstrap,GerHobbelt/bootstrap,joblocal/bootstrap,n054/bootstrap,andresgalante/bootstrap,Hemphill/bootstrap-docs,lemuelbarango/bootstrap,supergibbs/bootstrap,SweetProcess/bootstrap,andresgalante/bootstrap,tomlutzenberger/bootstrap,twbs/bootstrap,abvalentine/bootstrap,Lyricalz/bootstrap