Merge #14497: docs: Add doc/bitcoin-conf.md

1fb3c167c3 Add `doc/bitcoin-conf.md` (Hennadii Stepanov)

Pull request description:

  From the IRC:
  > 2018-10-16T05:35:03  \<wumpus\> if something can be solved by better documentation, please work on documentation!
  > 2018-10-16T05:35:12  \<wumpus\> don't change the code instead

  Refs:

  - #14370
  - #14427
  - #14494

  Based on the BITCOIN.CONF(5) manual page written by Micah Anderson \<micah@debian.org\> for the Debian system.

Tree-SHA512: 16393c9073c027fa1c46f8b59651e60b9a3159b3aeb9b3102040c292d2787f32b1ead5977957ac3ac0759a4bf626650a2325b68ad84320964ac089ffc2d3b4f4

doc/README.md

@@ -69,6 +69,7 @@ The Bitcoin repo's [root README](/README.md) contains relevant information on th
 
 ### Miscellaneous
 - [Assets Attribution](assets-attribution.md)
+- [bitcoin.conf Configuration File](bitcoin-conf.md)
 - [Files](files.md)
 - [Fuzz-testing](fuzzing.md)
 - [Reduce Traffic](reduce-traffic.md)