update Project-templates.md

docs/markdown/Project-templates.md

@@ -20,11 +20,30 @@ project. The result can be compiled as usual. For example compiling it
 with Ninja could be done like this:
 
 ```
-$ meson builddir
-$ ninja -C builddir
+$ meson setup builddir
+$ meson compile -C builddir
 ```
 
 The generator has many different projects and settings. They can all
 be listed by invoking the command `meson init --help`.
 
 This feature is available since Meson version 0.45.0.
+
+# Generate a build script for an existing project
+
+With `meson init` you can generate a build script for an existing
+project with existing project files by running the command in the
+root directory of your project. Meson currently supports this
+feature for `executable`, and `jar` projects.
+
+# Build after generation of template
+
+It is possible to have Meson generate a build directory from the
+`meson init` command without running `meson setup`. This is done
+by passing `-b` or `--build` switch.
+
+```console
+$ mkdir project_name
+$ cd project_name
+$ meson init --language=c --name=myproject --version=0.1 --build
+```