Fix some typos (#644)

* Update env_requirement.rst

* Update env_requirement.rst

docs/installation/env_requirement.rst

@@ -86,8 +86,7 @@ For python dependencies,
 
 .. note::
 
-    - For Android build, `ANDROID_NDK_HOME` must be confifigured by using ``export ANDROID_NDK_HOME=/path/to/ndk``
+    - For Android build, `ANDROID_NDK_HOME` must be configured by using ``export ANDROID_NDK_HOME=/path/to/ndk``.
     - It will link ``libc++`` instead of ``gnustl`` if ``NDK version >= r17b`` and ``bazel version >= 0.13.0``, please refer to `NDK cpp-support <https://developer.android.com/ndk/guides/cpp-support>`__.
     - For Mac, please install Homebrew at first before installing other dependencies. Set ANDROID_NDK_HOME in ``/etc/bashrc`` and then run ``source /etc/bashrc``.  This installation was tested with macOS Mojave(10.14).
 
-rs.
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