Dynamic width count for plugin registry table column

There might be chance that few plugin name and url
does not fit into hard coded column width and give error.

This commit count the column width as per plugins name.

Also display the number of plugins in new SR column.
Change-Id: Ia5736d2581ee3b6f851b8d08f855c2a19c157c47

doc/source/data/tempest-plugins-registry.header

@@ -17,7 +17,3 @@ Detected Plugins
 The following are plugins that a script has found in the openstack/
 namespace, which includes but is not limited to official OpenStack
 projects.
-
-+----------------------------+-------------------------------------------------------------------------+
-|Plugin Name                 |URL                                                                      |
-+----------------------------+-------------------------------------------------------------------------+

tools/generate-tempest-plugins-list.sh

@@ -49,13 +49,37 @@ fi
 
 sorted_plugins=$(python tools/generate-tempest-plugins-list.py)
 
+name_col_len=$(echo "${sorted_plugins}" | wc -L)
+name_col_len=$(( name_col_len + 2 ))
+
+# Print the title underline for a RST table.
+function title_underline {
+    printf "== "
+    local len=$1
+    while [[ $len -gt 0 ]]; do
+        printf "="
+        len=$(( len - 1))
+    done
+    printf " ===\n"
+}
+
+printf "\n\n"
+title_underline ${name_col_len}
+printf "%-3s %-${name_col_len}s %s\n" "SR" "Plugin Name" "URL"
+title_underline ${name_col_len}
+
+i=0
 for k in ${sorted_plugins}; do
+    i=$((i+1))
     project=${k:0:28}
     giturl="git://git.openstack.org/openstack/${k:0:26}"
-    printf "|%-28s|%-73s|\n" "${project}" "${giturl}"
+    printf "%-3s %-${name_col_len}s %s\n" "$i" "${project}" "${giturl}"
-    printf "+----------------------------+-------------------------------------------------------------------------+\n"
 done
 
+title_underline ${name_col_len}
+
+printf "\n\n"
+
 if [[ -r doc/source/data/tempest-plugins-registry.footer ]]; then
     cat doc/source/data/tempest-plugins-registry.footer
 fi