Fix broken links

[edwardalee]

This PR fixes a large number of broken links, fixing #240. Running yarn build no longer reports any broken links. It does still give a warning, one that I can't figure out:

[WARNING] {"moduleIdentifier":"/Users/edwardlee/git/lf-lang.github.io/node_modules/babel-loader/lib/index.js??ruleSet[1].rules[6].use[0]!/Users/edwardlee/git/lf-lang.github.io/src/components/LinguaFrancaMultiTargetUtils/DynamicMultiTargetCodeblock.tsx","moduleName":"./src/components/LinguaFrancaMultiTargetUtils/DynamicMultiTargetCodeblock.tsx","loc":"35:119-129","message":"Critical dependency: the request of a dependency is an expression","compilerPath":"server"}

I believe this is orthogonal to this PR, but it may prevent us from being able to treat warnings as fatal errors, which would help prevent broken links in the future.

[lhstrh]

👍

[lhstrh]

I think the warning is about webpack being confused because it encountered a dynamic import or require statement that it cannot resolve statically at build time.