net/gcoap: improved header documentation
net/gcoap: improved header documentation

- fixed/unified indention throughout the file
- use same style for @brief blocks
- removed colons from end of brief descriptions
- fixed in and out annotations for function parameters

gebart/RIOT,OTAkeys/RIOT,dailab/RIOT,beurdouche/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,kbumsik/RIOT,ks156/RIOT,kaleb-himes/RIOT,mfrey/RIOT,adjih/RIOT,authmillenon/RIOT,adjih/RIOT,Josar/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,mfrey/RIOT,x3ro/RIOT,adrianghc/RIOT,basilfx/RIOT,LudwigKnuepfer/RIOT,immesys/RiSyn,kerneltask/RIOT,hamilton-mote/RIOT-OS,roberthartung/RIOT,roberthartung/RIOT,kYc0o/RIOT,OTAkeys/RIOT,hamilton-mote/RIOT-OS,plushvoxel/RIOT,LudwigKnuepfer/RIOT,BytesGalore/RIOT,immesys/RiSyn,avmelnikoff/RIOT,immesys/RiSyn,kaleb-himes/RIOT,Josar/RIOT,Hyungsin/RIOT-OS,aeneby/RIOT,neiljay/RIOT,lazytech-org/RIOT,cladmi/RIOT,smlng/RIOT,BytesGalore/RIOT,dailab/RIOT,Hyungsin/RIOT-OS,mfrey/RIOT,LudwigKnuepfer/RIOT,neiljay/RIOT,OlegHahm/RIOT,jfischer-phytec-iot/RIOT,toonst/RIOT,avmelnikoff/RIOT,adrianghc/RIOT,plushvoxel/RIOT,hamilton-mote/RIOT-OS,miri64/RIOT,biboc/RIOT,yogo1212/RIOT,kaspar030/RIOT,yogo1212/RIOT,LudwigOrtmann/RIOT,adrianghc/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,LudwigOrtmann/RIOT,A-Paul/RIOT,dkm/RIOT,mtausig/RIOT,mtausig/RIOT,yogo1212/RIOT,Ell-i/RIOT,kbumsik/RIOT,x3ro/RIOT,adrianghc/RIOT,avmelnikoff/RIOT,smlng/RIOT,beurdouche/RIOT,neiljay/RIOT,kerneltask/RIOT,adjih/RIOT,jasonatran/RIOT,gebart/RIOT,cladmi/RIOT,mtausig/RIOT,ant9000/RIOT,lazytech-org/RIOT,kYc0o/RIOT,kaleb-himes/RIOT,Josar/RIOT,aeneby/RIOT,Hyungsin/RIOT-OS,gebart/RIOT,kYc0o/RIOT,ant9000/RIOT,LudwigOrtmann/RIOT,rfuentess/RIOT,neumodisch/RIOT,thomaseichinger/RIOT,rfuentess/RIOT,kYc0o/RIOT,lazytech-org/RIOT,A-Paul/RIOT,RIOT-OS/RIOT,beurdouche/RIOT,thomaseichinger/RIOT,Josar/RIOT,toonst/RIOT,kerneltask/RIOT,smlng/RIOT,neumodisch/RIOT,immesys/RiSyn,miri64/RIOT,smlng/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,x3ro/RIOT,plushvoxel/RIOT,adjih/RIOT,dailab/RIOT,miri64/RIOT,LudwigOrtmann/RIOT,dkm/RIOT,avmelnikoff/RIOT,hamilton-mote/RIOT-OS,toonst/RIOT,Ell-i/RIOT,authmillenon/RIOT,lazytech-org/RIOT,ks156/RIOT,Hyungsin/RIOT-OS,OlegHahm/RIOT,avmelnikoff/RIOT,toonst/RIOT,jfischer-phytec-iot/RIOT,jfischer-phytec-iot/RIOT,aeneby/RIOT,ant9000/RIOT,OTAkeys/RIOT,josephnoir/RIOT,jasonatran/RIOT,plushvoxel/RIOT,thomaseichinger/RIOT,neiljay/RIOT,Josar/RIOT,gebart/RIOT,ks156/RIOT,authmillenon/RIOT,x3ro/RIOT,kbumsik/RIOT,neiljay/RIOT,cladmi/RIOT,gebart/RIOT,cladmi/RIOT,mtausig/RIOT,OTAkeys/RIOT,kbumsik/RIOT,kaspar030/RIOT,kbumsik/RIOT,biboc/RIOT,basilfx/RIOT,jfischer-phytec-iot/RIOT,dkm/RIOT,authmillenon/RIOT,kaspar030/RIOT,BytesGalore/RIOT,miri64/RIOT,basilfx/RIOT,aeneby/RIOT,basilfx/RIOT,LudwigOrtmann/RIOT,immesys/RiSyn,biboc/RIOT,biboc/RIOT,mtausig/RIOT,josephnoir/RIOT,dkm/RIOT,immesys/RiSyn,rfuentess/RIOT,aeneby/RIOT,Ell-i/RIOT,rfuentess/RIOT,dailab/RIOT,dailab/RIOT,jfischer-phytec-iot/RIOT,LudwigKnuepfer/RIOT,yogo1212/RIOT,A-Paul/RIOT,mfrey/RIOT,neumodisch/RIOT,josephnoir/RIOT,rfuentess/RIOT,thomaseichinger/RIOT,Ell-i/RIOT,kYc0o/RIOT,roberthartung/RIOT,OlegHahm/RIOT,plushvoxel/RIOT,yogo1212/RIOT,kerneltask/RIOT,neumodisch/RIOT,neumodisch/RIOT,beurdouche/RIOT,Hyungsin/RIOT-OS,josephnoir/RIOT,smlng/RIOT,adjih/RIOT,kaspar030/RIOT,lazytech-org/RIOT,neumodisch/RIOT,OTAkeys/RIOT,BytesGalore/RIOT,LudwigKnuepfer/RIOT,ks156/RIOT,Ell-i/RIOT,x3ro/RIOT,OlegHahm/RIOT,ks156/RIOT,kerneltask/RIOT,thomaseichinger/RIOT,miri64/RIOT,kaleb-himes/RIOT,basilfx/RIOT,toonst/RIOT,roberthartung/RIOT,A-Paul/RIOT,hamilton-mote/RIOT-OS,yogo1212/RIOT,dkm/RIOT,kaspar030/RIOT,authmillenon/RIOT,ant9000/RIOT,beurdouche/RIOT,A-Paul/RIOT,BytesGalore/RIOT,roberthartung/RIOT,cladmi/RIOT,biboc/RIOT,LudwigOrtmann/RIOT,kaleb-himes/RIOT,josephnoir/RIOT,adrianghc/RIOT,mfrey/RIOT,RIOT-OS/RIOT