[doc/log] Fix markdown syntax and line terminate LogPrint

- Fix doxygen comment for payTxFee
- [doc] Fix markdown
- Make sure LogPrintf strings are line-terminated

Github-Pull: #7617
Rebased-From: fa06ce0949 fa97f95c15 fa26652459

doc/README.md

@@ -49,7 +49,7 @@ The following are developer notes on how to build Bitcoin on your native platfor
 
 Development
 ---------------------
-The Bitcoin repo's [root README](https://github.com/bitcoin/bitcoin/blob/master/README.md) contains relevant information on the development process and automated testing.
+The Bitcoin repo's [root README](/README.md) contains relevant information on the development process and automated testing.
 
 - [Developer Notes](developer-notes.md)
 - [Multiwallet Qt Development](multiwallet-qt.md)

doc/release-process.md

@@ -210,7 +210,7 @@ Note: check that SHA256SUMS itself doesn't end up in SHA256SUMS, which is a spur
 
   - Optionally reddit /r/Bitcoin, ... but this will usually sort out itself
 
-- Notify BlueMatt so that he can start building [https://launchpad.net/~bitcoin/+archive/ubuntu/bitcoin](the PPAs)
+- Notify BlueMatt so that he can start building [the PPAs](https://launchpad.net/~bitcoin/+archive/ubuntu/bitcoin)
 
 - Add release notes for the new version to the directory `doc/release-notes` in git master