Toolchain: Update Dockerfile to use gcc 11 and add texinfo package

Missed this in the gcc 11 version update, but if anyone is using this
then they'll need gcc 11 to build Lagom.

Toolchain/Dockerfile

@@ -8,8 +8,8 @@ RUN apt-get update -y \
         ccache \
         cmake \
         curl \
-        g++-10 \
-        gcc-10 \
+        g++-11 \
+        gcc-11 \
         e2fsprogs \
         genext2fs \
         git \
@@ -25,7 +25,8 @@ RUN apt-get update -y \
         qemu-utils \
         rsync \
         sudo \
+        texinfo \
         tzdata \
         unzip \
     && rm -rf /var/lib/apt/lists/ \
-    && update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 900 --slave /usr/bin/g++ g++ /usr/bin/g++-10
+    && update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 900 --slave /usr/bin/g++ g++ /usr/bin/g++-11