erts: Improve READEME.pcre_update.md

Author: sverker

erts/emulator/pcre/README.pcre_update.md

@@ -238,9 +238,9 @@ like this in the C source:
 When building, pcre2\_match\_loop\_break\_cases.gen.h will be generated
 during build by pcre.mk, it will look like:
 
-     case 791: goto L_LOOP_COUNT_691;
-     case 1892: goto L_LOOP_COUNT_1792;
-     case 1999: goto L_LOOP_COUNT_1899;
+     case 791: goto L_LOOP_COUNT_791;
+     case 1892: goto L_LOOP_COUNT_1892;
+     case 1999: goto L_LOOP_COUNT_1999;
 
 etc
 
@@ -304,12 +304,11 @@ from pcre.mk. Note that you will need to put things back in order in
 pcre.mk after all testing is done. Once a 'make' is successful, you
 can generate new dependencies:
 
-    ~/tmp/pcre/epcre-8.33> gcc -MM -c -g -O2 -DHAVE_CONFIG_H -I/ldisk/pan/git/otp/erts/x86_64-unknown-linux-gnu -DERLANG_INTEGRATION *.c | grep -v $ERL_TOP
+    ~/tmp/pcre/epcre-8.33> gcc -MM -c -DERLANG_INTEGRATION *.c | sed ...
 
-Well, then you have to add $(PCRE\_OBJDIR)/ to each object and
-$(PCRE\_DIR)/ to each header. I did it manually, it's just a couple of
-files. Now your pcre.mk is fairly up to date and it's time to start
-patching in the changes...
+pcre.mk contains a full gcc command line with sed that adds $(PCRE\_OBJDIR)/
+to each object file and $(PCRE\_DIR)/ to each source file. Now your pcre.mk is
+fairly up to date and it's time to start patching in the changes...
 
 ## Updating pcre2_match.c
 
@@ -473,7 +472,7 @@ fix whatever you did in pcre.mk to make it build locally.
 ## Update test suites
 
 The next step is to integrate the updated PCRE2 tests into our test suites.
-Copy testoutput[1-5,10] from the testdata directory of your new version
+Copy testoutput[1,2,4,5,10] from the testdata directory of your new version
 of pcre2, to the re\_SUITE\_data in stdlib's test suites. Run the
 test suites and remove any bugs. Usually the bugs come from the fact
 that the PCRE test suites get better and from our implementation of