Remove reference to more_headers module (#3323)

These references are leftovers and are not used anymore.

Merge pull request #126 from mindreeper2420/learn-more6

fix(content): update planning content and page titles

Merge pull request #125 from mindreeper2420/learn-more5

fix(headers): update alignment of page headers

Merge pull request #124 from mindreeper2420/learn-more4

fix(heading): remove extra heading from Planning page

Merge pull request #121 from mindreeper2420/learn-more3

fix(cards): update icons and text