Reformat container doc
Reformat container doc

- split the doc into sections for simple and extended format and move
  example layouts to the end.
- use ASCII tables to describe chunk formats
- attempt to consistently use MUST/SHOULD, etc.
- remove bold from most terms, but add them to definition lists which
  allow for the styling to be changed.

Change-Id: I93c1cd33bde9ccf0b265b202ec4182ce98fd6b48

kim42083/webm.libwebp,abwiz0086/webm.libwebp,matanbs/webm.libwebp,redengineer/libwebp,ericmckean/webm.libwebp,imazen/libwebp,jacklicn/libwebp,zofuthan/libwebp,zofuthan/libwebp,altogother/webm.libwebp,reimaginemedia/webm.libwebp,dumganhar/libwebp,iniwf/webm.libwebp,Acidburn0zzz/webm.libwebp,jacklicn/libwebp,cysp/libwebp,Suvarna1488/webm.libwebp,keane83/BLE_IM,Acidburn0zzz/webm.libwebp,redengineer/libwebp,jiehu5114/libwebp,dumganhar/libwebp,jiehu5114/libwebp,yohunl/libwebp,PKRoma/libwebp,iniwf/webm.libwebp,keane83/BLE_IM,Suvarna1488/webm.libwebp,PKRoma/libwebp,comoyo/gonzo-libwebp,appunite/libwebp,kalli123/webm.libwebp,iniwf/webm.libwebp,zofuthan/libwebp,gshORTON/webm.libwebp,Tekserve/libwebp,Tekserve/libwebp,altogother/webm.libwebp,ericmckean/webm.libwebp,Suvarna1488/webm.libwebp,jiehu5114/libwebp,ya7lelkom/libwebp,zofuthan/libwebp,rxl194/libwebp,ttyangf/libwebp,yohunl/libwebp,PKRoma/libwebp,cysp/libwebp,appunite/libwebp,appunite/libwebp,webmproject/libwebp,reimaginemedia/webm.libwebp,matanbs/webm.libwebp,abwiz0086/webm.libwebp,gshORTON/webm.libwebp,imazen/libwebp,kim42083/webm.libwebp,ya7lelkom/libwebp,imazen/libwebp,yohunl/libwebp,ttyangf/libwebp,jacklicn/libwebp,comoyo/gonzo-libwebp,Tekserve/libwebp,altogother/webm.libwebp,ya7lelkom/libwebp,comoyo/gonzo-libwebp,redengineer/libwebp,kalli123/webm.libwebp,redengineer/libwebp,yohunl/libwebp,imazen/libwebp,Suvarna1488/webm.libwebp,jacklicn/libwebp,rxl194/libwebp,jiehu5114/libwebp,reimaginemedia/webm.libwebp,kim42083/webm.libwebp,webmproject/libwebp,kleopatra999/webm.libwebp,kleopatra999/webm.libwebp,appunite/libwebp,altogother/webm.libwebp,Aexyn/libwebp,Maria1099/webm.libwebp,kim42083/webm.libwebp,PKRoma/libwebp,rxl194/libwebp,jiehu5114/libwebp,zofuthan/libwebp,iniwf/webm.libwebp,matanbs/webm.libwebp,Distrotech/libwebp,kim42083/webm.libwebp,Aexyn/libwebp,cysp/libwebp,Aexyn/libwebp,ya7lelkom/libwebp,rxl194/libwebp,altogother/webm.libwebp,abwiz0086/webm.libwebp,matanbs/webm.libwebp,webmproject/libwebp,yohunl/libwebp,Maria1099/webm.libwebp,keane83/BLE_IM,appunite/libwebp,reimaginemedia/webm.libwebp,comoyo/gonzo-libwebp,Suvarna1488/webm.libwebp,appunite/libwebp,PKRoma/libwebp,Aexyn/libwebp,jacklicn/libwebp,matanbs/webm.libwebp,Maria1099/webm.libwebp,ttyangf/libwebp,PKRoma/libwebp,ericmckean/webm.libwebp,Maria1099/webm.libwebp,keane83/BLE_IM,webmproject/libwebp,ttyangf/libwebp,Distrotech/libwebp,kalli123/webm.libwebp,cysp/libwebp,comoyo/gonzo-libwebp,comoyo/gonzo-libwebp,ttyangf/libwebp,Aexyn/libwebp,Acidburn0zzz/webm.libwebp,comoyo/gonzo-libwebp,Acidburn0zzz/webm.libwebp,imazen/libwebp,iniwf/webm.libwebp,reimaginemedia/webm.libwebp,keane83/BLE_IM,rxl194/libwebp,dumganhar/libwebp,redengineer/libwebp,Tekserve/libwebp,kalli123/webm.libwebp,abwiz0086/webm.libwebp,kleopatra999/webm.libwebp,gshORTON/webm.libwebp,kleopatra999/webm.libwebp,kalli123/webm.libwebp,Distrotech/libwebp,ya7lelkom/libwebp,Maria1099/webm.libwebp,ericmckean/webm.libwebp,kleopatra999/webm.libwebp,Acidburn0zzz/webm.libwebp,gshORTON/webm.libwebp,gshORTON/webm.libwebp,ericmckean/webm.libwebp,webmproject/libwebp,abwiz0086/webm.libwebp