Fix typos

Fixed with:
perl -pe "s/Descripion/Description/" -i src/demod*.c
codespell -w src/symbols.c

Author: dforsi

Diff for: src/demod.c

@@ -906,7 +906,7 @@ int demod_get_sample (int a)
  *
  * Returns:	None 
  *
- * Descripion:	We start off with two bandpass filters tuned to
+ * Description:	We start off with two bandpass filters tuned to
  *		the given frequencies.  In the case of VHF packet
  *		radio, this would be 1200 and 2200 Hz.
  *

Diff for: src/demod_9600.c

@@ -336,7 +336,7 @@ void demod_9600_init (enum modem_t modem_type, int original_sample_rate, int ups
  *
  * Returns:	None 
  *
- * Descripion:	"9600 baud" packet is FSK for an FM voice transceiver.
+ * Description:	"9600 baud" packet is FSK for an FM voice transceiver.
  *		By the time it gets here, it's really a baseband signal.
  *		At one extreme, we could have a 4800 Hz square wave.
  *		A the other extreme, we could go a considerable number

Diff for: src/demod_afsk.c

@@ -532,7 +532,7 @@ void demod_afsk_init (int samples_per_sec, int baud, int mark_freq,
  *
  * Returns:	None 
  *
- * Descripion:	First demodulate the AFSK signal.
+ * Description:	First demodulate the AFSK signal.
  *
  *		A digital phase locked loop (PLL) recovers the symbol
  *		clock and picks out data bits at the proper rate.

Diff for: src/demod_psk.c

@@ -624,7 +624,7 @@ static inline int phase_shift_to_symbol (float phase_shift, int bits_per_symbol,
  *
  * Returns:	None 
  *
- * Descripion:	All the literature, that I could find, described mixing
+ * Description:	All the literature, that I could find, described mixing
  *		with a local oscillator.  First we multiply the input by
  *		cos and sin then low pass filter each.  This gives us
  *		correlation to the different phases.  The signs of these two

Diff for: src/symbols.c

@@ -681,7 +681,7 @@ void symbols_from_dest_or_src (char dti, char *src, char *dest, char *symtab, ch
 
 // The position and object formats all contain a proper symbol and table.
 // There doesn't seem to be much reason to have a symbol for something without
-// a postion because it would not show up on a map.
+// a position because it would not show up on a map.
 // This just seems to be a remnant of something used long ago and no longer needed.
 // The protocol spec mentions a "MIM tracker" but I can't find any references to it.