Fix typo in documentation

There were a number of places where library was misspelt. This commit
fixes those typos.

docs/install_pip.rst

@@ -20,7 +20,7 @@ This might fail if certain libraries are installed in non-standard locations.
 In this case, add the paths for these libraries to both the LIBRARY_PATH and
 LD_LIBRARY_PATH environmental variables before running pip::
 
-    export LIBRARY_PATH=$LIBARY_PATH:/path/to/lib:/other/path/to/lib
+    export LIBRARY_PATH=$LIBRARY_PATH:/path/to/lib:/other/path/to/lib
     export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path/to/lib:/other/path/to/lib
 
 If you would rather install from source (e.g. to work on a development branch),

src/SBInterpolatedImage.cpp

@@ -1279,7 +1279,7 @@ namespace galsim {
         assert(N>=0);
         checkReadyToShoot();
         /* The pixel coordinates are stored by cumulative absolute flux in
-         * a C++ standard-libary set, so the inversion is done with a binary
+         * a C++ standard-library set, so the inversion is done with a binary
          * search tree.  There are no doubt speed gains available from sorting the
          * pixels by flux, and somehow weighting the tree search to the elements holding
          * the most flux.  But I'm doing it the simplest way right now.