[string.insert] Change "pos1" to "pos" for overloads taking one position

Also make argument names in synopsis consistent.

Fixes #1338

Author: jwakely

source/strings.tex

@@ -1002,10 +1002,10 @@
       basic_string& assign(InputIterator first, InputIterator last);
     basic_string& assign(initializer_list<charT>);
 
-    basic_string& insert(size_type pos1, const basic_string& str);
+    basic_string& insert(size_type pos, const basic_string& str);
     basic_string& insert(size_type pos1, const basic_string& str,
                          size_type pos2, size_type n = npos);
-    basic_string& insert(size_type pos1, basic_string_view<charT, traits> sv);
+    basic_string& insert(size_type pos, basic_string_view<charT, traits> sv);
     template<class T>
       basic_string& insert(size_type pos1, const T& t,
                            size_type pos2, size_type n = npos);
@@ -2361,7 +2361,7 @@
 \indexlibrarymember{insert}{basic_string}%
 \begin{itemdecl}
 basic_string&
-  insert(size_type pos1,
+  insert(size_type pos,
          const basic_string& str);
 \end{itemdecl}
 
@@ -2400,13 +2400,13 @@
 
 \indexlibrarymember{insert}{basic_string}%
 \begin{itemdecl}
-basic_string& insert(size_type pos1, basic_string_view<charT, traits> sv);
+basic_string& insert(size_type pos, basic_string_view<charT, traits> sv);
 \end{itemdecl}
 
 \begin{itemdescr}
 \pnum
 \effects
-Equivalent to: \tcode{return insert(pos1, sv.data(), sv.size());}
+Equivalent to: \tcode{return insert(pos, sv.data(), sv.size());}
 \end{itemdescr}
 
 \indexlibrarymember{insert}{basic_string}%