Add capabilities to get and render manpage output in the Web UI (#881)

- class method to get arbitrary file contents
- new web UI endpoint to fetch the contents of rascsi man pages (rendered txt files)
- Link to manpage in page footer
- Link to new wiki page for image type docs
- Other UI tweaks

python/common/src/rascsi/sys_cmds.py

@@ -181,3 +181,15 @@ class SysCmds:
             return process.returncode, process.stdout.decode("utf-8")
 
         return process.returncode, process.stderr.decode("utf-8")
+
+    @staticmethod
+    def get_filecontents(file_path):
+        """
+        Takes (str) file_path, with the path to the file to fetch the contents of.
+        Returns either the file contents, or the exception error.
+        """
+        try:
+            with open(file_path) as file:
+                return 0, file.read()
+        except Exception as error:
+            return 1, error