Strategy for consolidation of hyperlinks to central documentation

[al-fisher]

Following/as part of close out of #92 and the restructuring of documentation navigation...
A suggested strategy for consolidation of hyperlinks

We have a large number of references to various sub-pages of the BHoM docs across READMEs and other locations from outside of the BHoM documentation itself.
Suggesting a series of possible actions to consolidate curated links to small number of core repos and locations.
With the wider repos and standard templates being simplified to just point to high level https://bhom.xyz/documentation/ (as the search now is pretty good!)

Then suggesting we set up GitHub actions specifically on these small numbers of repos to potentially support the checking validity of URLs.
This can be in support of wider review of documentation strategy for our code being looked at by @travispotterBH, @michaelhoehn and others too.

We should also create a Documentation page outlining our documentation strategy. (We already have a nice page on editing, but one to outline the structure and approach will be good 🐶🥫 😄)

So a proposed list of actions for closing out or raising as discrete issues as appropriate are below:

• Starting with
  Standardise approach to links and file names see #86
• Update links in READMEs for core repos
  BHoM, BHoM/BHoM#1568
  BHoM_Engine, BHoM/BHoM_Engine#3222
  BHoM_Adapter, BHoM/BHoM_Adapter#379
  BHoM_UI, BHoM/BHoM_UI#474
  template-repository BHoM/template-repository#25 and
  documentation (not needed)
• Remove all sub-links to documentation across the wider repos, replacing with new standard block of text just pointing to bhom.xyz/documentation top level - minimising duplication and maintenance.
• Create new documentation strategy as page in documentation
• Set up GitHub Actions to flag invalid URLs on core repos (same short list as above)

@alelom, @FraserGreenroyd fyi