Update and clarify 1.14.5 release notes

[patricklodder]

IMPORTANT: I changed the reservations around BDB 5.3 upgrades, as this was confirmed to not cause any issues and I personally have not experienced any issues on either Ubuntu (20.04, 21.04) and macOS since, having switched between wallets created with both versions multiple times. If there is ANY doubt that there is a compatibility issue, then we MUST revert this change because this is a minor release.

Updated the 1.14.5 release notes to:

• Include final code changes
• Explicitly mention that this now contains an important security update and recommend immediate update
• Clarify the new fee recommendation
  • Split wallet and relay policy changes
  • Link to the new recommendation document
  • Elaborate benefits and workarounds
  • Fix the wallet fee to be 0.01 DOGE, not 0.001.
• Reworded the version display in terms of user benefits instead of developer benefits.
• Shortened the section on key derivation path to be more concise, confident and just list the benefit.
• Reworded the section on the re-added auxpow methods, focusing on actual miner benefits
• Separated the RPC API changes as that's always a section of its own.
• Created a section about build system and CI, because those affect the useful life and thought it more useful to combine multiple improvements there
• Minor changes:
  • removed some of the individual commit changes that are now mentioned under the build system change
  • Added pruning test because in the past advice has been given that pruning doesn't work, and now it's proven to work
  • Reworded some of the changes to be more concise
• Fixed hard line endings to be more consistent with 80 characters (it was done in some places but not others)

[rnicoll]

One nit pick to clarify for non-technical users, then good to merge.

Realised I could check the BDB release notes, they confirm database file format has not changed:

• https://download.oracle.com/otndocs/products/berkeleydb/html/changelog_5_3.html#idp636088
• https://download.oracle.com/otndocs/products/berkeleydb/html/changelog_5_2.html#idp600136

Log format has changed, in case we want to note it's important to ensure the node has shut down before upgrading, but I think we're okay to leave that.

[patricklodder]

Drafting notes to include additional security fix for #2672.

[patricklodder]

Updated to fix @edtubbs' comment and squash-rebased.