explaination of stack layout

Signed-off-by: Mattias Andrée <maandree@operamail.com>
explaination of margin layout

Signed-off-by: Mattias Andrée <maandree@operamail.com>
add typo

Signed-off-by: Mattias Andrée <maandree@operamail.com>
explaination of line layout

Signed-off-by: Mattias Andrée <maandree@operamail.com>
explaination of flow layout

Signed-off-by: Mattias Andrée <maandree@operamail.com>
explaination of dock layout

Signed-off-by: Mattias Andrée <maandree@operamail.com>
add gravity layout to todo

Signed-off-by: Mattias Andrée <maandree@operamail.com>