Add all env. vars. used to pass mojo lib. search paths to tutorial

The env. var. shown in the tutorial section of the development document
for the Stdlib is (at least in some cases) insufficient to point `mojo`
to a newly build stdlib.mjpkg. This adds all the same variable that are
passed in the `lit` config to hopefully get all edge cases covered and
make getting stared easier.

Signed-off-by: Hristo I. Gueorguiev <53634432+izo0x90@users.noreply.github.com>

stdlib/docs/development.md

@@ -262,11 +262,14 @@ def main():
     print(all_paths.__str__())
 ```
 
-We also need to set the following environment variable that tells Mojo to
+We also need to set the following environment variables that tells Mojo to
 prioritize imports from the standard library we just built, over the one that
 ships with Mojo:
 
 ```bash
+MODULAR_MOJO_IMPORT_PATH=../build \
+MODULAR_MOJO_MAX_IMPORT_PATH=../build \
+MODULAR_MOJO_MAX_NIGHTLY_IMPORT_PATH=../build \
 MODULAR_MOJO_NIGHTLY_IMPORT_PATH=../build mojo main.mojo
 ```
 
@@ -288,6 +291,9 @@ you can get with `sudo apt install entr` on Linux, or `brew install entr` on
 macOS. Now run:
 
 ```bash
+export MODULAR_MOJO_IMPORT_PATH=../build
+export MODULAR_MOJO_MAX_IMPORT_PATH=../build
+export MODULAR_MOJO_MAX_NIGHTLY_IMPORT_PATH=../build
 export MODULAR_MOJO_NIGHTLY_IMPORT_PATH=../build
 
 ls **/*.mojo | entr sh -c "./scripts/build-stdlib.sh && mojo main.mojo"