Update build docs for current depends baseline

depends/README.md

@@ -2,7 +2,7 @@
 
 To build dependencies for the current arch+OS:
 
-    make
+    make HOST=x86_64-pc-linux-gnu NO_QT=0
 
 To build for another arch/OS:
 
@@ -10,7 +10,7 @@ To build for another arch/OS:
 
 For example:
 
-    make HOST=x86_64-w64-mingw32 -j4
+    make HOST=x86_64-w64-mingw32 NO_QT=0 -j1
 
 A prefix will be generated that's suitable for plugging into Agrarian's
 configure. In the above example, a dir named x86_64-w64-mingw32 will be
@@ -30,6 +30,17 @@ Common `host-platform-triplets` for cross compilation are:
 
 No other options are needed, the paths are automatically configured.
 
+For the current Agrarian 2.0 branch, the preferred user-facing build entry
+points are the helpers in `contrib/`:
+
+- `contrib/build-linux.sh`
+- `contrib/build-linux-wallet.sh`
+- `contrib/build-win64-wallet.sh`
+- `contrib/agrarian-build-menu.sh`
+
+Those helpers set the correct Qt, host-tool, and protobuf paths around the
+depends prefix.
+
 ### Install the required dependencies: Ubuntu & Debian
 
 #### For macOS cross compilation
@@ -44,7 +55,21 @@ No other options are needed, the paths are automatically configured.
 
 Common linux dependencies:
 
-    sudo apt-get install make automake cmake curl g++-multilib libtool binutils-gold bsdmainutils pkg-config python3 patch
+    sudo apt-get install make automake cmake curl git g++-multilib libtool binutils-gold bsdmainutils pkg-config python3 patch bzip2 xz-utils
+
+Native Linux Qt wallet builds also need the desktop development headers used by
+Qt's xcb/font stack:
+
+    sudo apt-get install libfontconfig1-dev libfreetype-dev libharfbuzz-dev \
+      libbrotli-dev libbz2-dev libexpat1-dev libglib2.0-dev \
+      libgraphite2-dev libpng-dev zlib1g-dev libx11-xcb-dev \
+      libxcb1-dev libxcb-cursor-dev libxcb-icccm4-dev libxcb-image0-dev \
+      libxcb-keysyms1-dev libxcb-randr0-dev libxcb-render0-dev \
+      libxcb-render-util0-dev libxcb-shape0-dev libxcb-shm0-dev \
+      libxcb-sync-dev libxcb-util-dev libxcb-xfixes0-dev \
+      libxcb-xinerama0-dev libxcb-xkb-dev libxau-dev libxdmcp-dev \
+      libxext-dev libxi-dev libxrender-dev libxkbcommon-dev \
+      libxkbcommon-x11-dev
 
 For linux ARM cross compilation: