Merge pull request #358 from vkucera/troubleshooting-shmem

Troubleshooting: Rephrase the help for the shm error

Author: dsekihat

docs/troubleshooting/README.md

@@ -180,12 +180,20 @@ Error in <TJAlienConnectionManager>: Failed to connect to any server! Giving up
 - You should be greeted with `Welcome to the ALICE GRID`.
 - Exit with `exit`.
 
-### shmem: could not create a message of size ...
+### Could not create a message
 
-Add `--shm-segment-size 1000000000` (or larger number) to your o2 command.
-It is due to shared memory segment that is probably outdated for the size of the intermediate tables you have. It is actually set as 90% of system's max VSIZE allowance set in limits, or 2GB if the limits cannot be found, which is probably what happens in your case.
+Error message:
+
+```text
+shmem: could not create a message of size ...
+```
+
+The shared-memory segment is probably too small for the size of the intermediate tables you have.
+It is set as 90 % of system's maximum `VSIZE` set in limits or 2 GB, if the limits cannot be found, which is probably what happens in your case.
+
+Set `--shm-segment-size 1000000000` (or larger) in your O2 command.
 
-## Graphical issue with high DPI monitors
+## Graphical issue with high-DPI monitors
 
 When using monitors with high DPI the labels and text in TBrowser might be too small, especially when fractional scaling is enabled in multiple
 monitors setup. A workaround for this issue is to create a local .rootrc file in the $HOME folder including the following lines, edited with your own