Merge bitcoin/bitcoin#33088: doc: move cmake -B build -LH up in Unix build docs

6757052 doc: move `cmake -B build -LH` up in Unix build docs (Bufo)

Pull request description:

  #32269 rebased.

  > I had trouble building bitcoin core the way I wanted since now more features require a flag while building. IMO it makes sense to make it a bit more prominent in the build docs how to get the needed flags.

  > Related issue: bitcoin/bitcoin#32258

ACKs for top commit:
  maflcko:
    lgtm ACK 6757052
  stickies-v:
    ACK 6757052
  janb84:
    ACK 6757052

Tree-SHA512: 8e6dc1e432c067f862560776176112d5c24c4009bdf8e9a4e8d1ea3328b88732188fc4d8a7cd29f8a9ed8a1809a7a8a86d63b7ae3ec4ebae74be466727c8d730

Author: fanquake

doc/build-unix.md

@@ -9,6 +9,10 @@ To Build
 
 ```bash
 cmake -B build
+```
+Run `cmake -B build -LH` to see the full list of available options.
+
+```bash
 cmake --build build    # Append "-j N" for N parallel jobs
 cmake --install build  # Optional
 ```
@@ -156,13 +160,6 @@ In this case there is no dependency on SQLite.
 
 Mining is also possible in disable-wallet mode using the `getblocktemplate` RPC call.
 
-Additional Configure Flags
---------------------------
-A list of additional configure flags can be displayed with:
-
-    cmake -B build -LH
-
-
 Setup and Build Example: Arch Linux
 -----------------------------------
 This example lists the steps necessary to setup and build a command line only distribution of the latest changes on Arch Linux: