build: tidy up comments in create_expfile.sh

Fixes spelling, adds punctuation and rewords some sentences for
readability in the comments of `tools/create_expfile.sh`.

PR-URL: #26220
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: richardlau

tools/create_expfile.sh

@@ -1,44 +1,45 @@
 #!/bin/sh
-# This script writes out all the exported symbols to a file
-# AIX needs this as sybmols are not exported by an
-# executable by default and we need to list
-# them specifically in order to export them
-# so that they can be used by native add-ons
+# Writes out all of the exported symbols to a file.
+# This is needed on AIX as symbols are not exported
+# by an executable by default and need to be listed
+# specifically for export so that they can be used
+# by native add-ons.
 #
-# The raw symbol data is objtained by using nm on
-# the .a files which make up the node executable
+# The raw symbol data is obtained by using nm on
+# the .a files which make up the node executable.
 #
-# -Xany makes sure we get symbols on both
-# 32 bit and 64 bit as by default we'd only get those
-# for 32 bit
+# -Xany processes symbols for both 32-bit and
+# 64-bit (the default is for 32-bit only).
 #
-# -g selects only exported symbols
+# -g selects only exported symbols.
 #
-# -C, -B and -p ensure the output is in a format we
-# can easily parse and convert into the symbol we need
+# -C, -B and -p ensure that the output is in a
+# format that can be easily parsed and converted
+# into the required symbol.
 #
-# -C suppresses the demangling of C++ names
-# -B gives us output in BSD format
-# -p displays the info in a standard portable output format
+# -C suppresses the demangling of C++ names.
+# -B writes the output in BSD format.
+# -p displays the info in a standard portable
+#    output format.
 #
-# We only include symbols if they are of the
-# following types and don't start with a dot.
+# Only include symbols if they are of the following
+# types and don't start with a dot.
 #
-# T - Global text symbol
-# D - Global data symbol
-# B - Gobal bss symbol.
+# T - Global text symbol.
+# D - Global data symbol.
+# B - Global bss symbol.
 #
-# the final sort allows us to remove any duplicates
+# The final sort allows removal of any duplicates.
 #
-# We need to exclude gtest libraries as they are not
-# linked into the node executable
+# Symbols for the gtest libraries are excluded as
+# they are not linked into the node executable.
 #
 echo "Searching $1 to write out expfile to $2"
 
-# this special sequence must be at the start of the exp file
+# This special sequence must be at the start of the exp file.
 echo "#!." > $2.tmp
 
-# pull the symbols from the .a files
+# Pull the symbols from the .a files.
 find $1 -name "*.a" | grep -v gtest \
   | xargs nm -Xany -BCpg \
   | awk '{