Fix extras install commands for zsh compatibility and remove duplicate moabb

Quote pip install extras commands in docs to prevent zsh glob interpretation,
and remove duplicate moabb entry from brain extras in pyproject.toml.

Closes #17

Author: bruAristimunha

docs/source/installation.rst

@@ -49,7 +49,7 @@ For EEG and fMRI applications:
 
 .. code-block:: bash
 
-   pip install spd_learn[brain]
+   pip install "spd_learn[brain]"
 
 This installs:
 
@@ -64,7 +64,7 @@ To build the documentation locally:
 
 .. code-block:: bash
 
-   pip install spd_learn[docs]
+   pip install "spd_learn[docs]"
 
 Testing
 ^^^^^^^
@@ -73,7 +73,7 @@ For running the test suite:
 
 .. code-block:: bash
 
-   pip install spd_learn[tests]
+   pip install "spd_learn[tests]"
 
 All Dependencies
 ^^^^^^^^^^^^^^^^
@@ -82,7 +82,7 @@ To install all optional dependencies:
 
 .. code-block:: bash
 
-   pip install spd_learn[all]
+   pip install "spd_learn[all]"
 
 Verifying Installation
 ----------------------

pyproject.toml

@@ -74,7 +74,6 @@ docs = [
 brain = [
     'moabb',
     'braindecode',
-    'moabb',
     'nilearn',
     'pyriemann',
     'skada',