[!706] Document the --skipversioncheck option of dunecontrol

Merge branch 'document-skipversioncheck' into 'master'

ref:core/dune-common Apparently, this option has been around since 2009, but
somehow it never made it into the man page and the output of -h.

See merge request [!706]

  [!706]: gitlab.dune-project.org/core/dune-common/merge_requests/706

bin/dunecontrol

@@ -742,6 +742,7 @@ usage () {
     echo "      --resume        resume a previous run (only consider the modules"
     echo "                      not built successfully on the previous run)"
     echo "      --skipfirst     skip the first module (use with --resume)"
+    echo "      --skipversioncheck      do not perform version checks when looking for other Dune modules"
     echo "      --opts=FILE     load default options from FILE"
     echo "      --builddir=NAME make out-of-source builds in a subdir NAME."
     echo "                      This directory is created inside each module."

doc/dunecontrol.1

@@ -136,6 +136,10 @@ Resume a previous run (only consider the modules not built successfully on the p
 .IP
 Skip the first module (use with --resume)
 .HP
+\fB--skipversioncheck\fP
+.IP
+When looking for Dune modules, do not check whether they have the required versions
+.HP
 \fB--opts=\fP\fIfile\fP
 .IP
 Load default options from \fIfile\fP