Collecting hopefully useful info for newly-joined contributors to start.

README.beginner-developer

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+    This is some collection to help recently joined coders to start with.
+    You can try the hard way. Then you just do not need to read any further.
+    Beleive me, at least for me, adds unnecessary frustration.
+    You lean back, feeling as (almost) on top of the World -- just to have to
+    learn somewhat later when asking for merge your work, that you are far from done...
+
+    In spite of every effort, this doc will (and can) never become complete.
+    Any comments, critisisms, suggestions, improvement requests are
+    and will   a l w a y s   and   f o r e v e r   remain   W E L C O M E .
+
+    To begin with, each project using any computer language, ususally is built upon
+    - partly some project conventions
+    - partly some personal tastes.
+
+    Individual tastes are no problem for one-man projects.
+    However, for bigger and long-lasting projects, individual tastes obviously
+    do not help readibility or maintenability.
+    My personal note, IMHO project conventions are also mainly of
+    personal taste of somebody in the project much before you joined ;-) ...
+
+    The following is the list we could collect so far.
+    This list is only numbered for easy reference.
+    This list is not considered to be sorted upon importance,
+    nor do I think there could be any such importance.
+    Please never re-number this list.
+    In case anybody feels in absolute need of picking some points upon importance,
+    please simply use a list in the header immediately below this introduction, like:
+
+important by HA5SE:	1, 2, 3			// sample
+
+
+
+Currently documented conventions
+================================
+
+
+1)  TLF is a combination of old code mixed with many new updates.
+    Old code is as-is, you should never count on conventions in old
+    code would still continue to be considered as current.
+
+    Recent code uses different conventions.
+
+    Code is considered old when before ...
+
+    You can check the age of any line or block using
+
+    git blame ...
+
+
+2)  No need to update Changelog . It only will be updated once for all changes so far
+    for each single new release by the maintainer. [thanks to HA5CQZ]
+
+
+3)  In turn, it is your responsibility to update the manual page  tlf.1.in  if your contribution
+    brings in visible changes to end-users. Such changes include e.g. new config keywords.
+
+
+4)  Do not include your callsign or reason or similar in your modification. [thanks to HA5CQZ]
+    No need to anything like
+
+    // 2021-02-01 HA5SE implementing TUNE_LNG=
+
+    Instead of comments like that, rather count on   "git blame"
+
+
+5)  When defining global variables we have to choices: [thanks to DL1JBE]
+
+    - Variables which are only part of an module should be defined in the module itself
+    and made known to other modules by declaring them extern in the modules header file
+    - Alternatively if the variable is not clearly related to a functional module we have
+    concentrated them in one place - at the moment in main.c (with test/data.c a shadow
+    copy for testing purposes). The variable should then be declared in globalvars.h