Fix some spelling mistakes highlighted by new codespell version

docs/source/matrix/ntpmat.rst

@@ -13,7 +13,7 @@ This page describes the functionality for :math:`n \times n` matrices over the
 finite quotient of the usual semiring of natural number by the congruence
 :math:`t = t + p` for arbitrary :math:`n`, :math:`t`, and :math:`p`. The value
 :math:`t` is referred to as the *threshold* and :math:`p` is called the
-*period*. The matrices of this type are referred to by the acroynm **ntp**
+*period*. The matrices of this type are referred to by the acronym **ntp**
 matrices, for "natural threshold period".  The :cpp:any:`NTPSemiring` has
 elements :math:`\{0, 1, ..., t, t +  1, ..., t + p - 1\}` where  :math:`t`, and
 :math:`p` are the threshold and period, respectively; addition and

include/libsemigroups/pbr.hpp

@@ -93,7 +93,7 @@ namespace libsemigroups {
     //! \no_libsemigroups_except
     explicit PBR(size_t n);
 
-    //! Construct from adjancencies \c 1 to \c n and \c -1 to \c
+    //! Construct from adjacencies \c 1 to \c n and \c -1 to \c
     //! -n.
     //!
     //! The parameters \p left and \p right should be containers of

src/todd-coxeter.cpp

@@ -2270,7 +2270,7 @@ namespace libsemigroups {
         push_settings();
         do_pop_settings = true;
         // The call to process_deductions in the main loop below could
-        // potentially accummulate large numbers of preferred definitions in
+        // potentially accumulate large numbers of preferred definitions in
         // the queue if the preferred_defs() setting is
         // options::preferred_defs::deferred, so we change it.
         preferred_defs(options::preferred_defs::none);